The update to dkms did not help. A piece of output from pulseaudio, once audio playback is broken, when playing a video with mplayer:

# tail -f /var/log/syslog
Jul 19 12:45:34  pulseaudio[4457]: last message repeated 10 times
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] client.c: Created 4 "Native client (UNIX socket client)"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Protocol version: remote 27, local 27
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Got credentials: uid=1000 gid=1000 success=1
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: SHM possible: yes
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Negotiated SHM: yes
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-augment-properties.c: Looking for .desktop file for mplayer
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-stream-restore.c: Restoring device for stream sink-input-by-application-name:MPlayer.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-intended-roles.c: Not setting device for stream audio stream, because already set.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c: Trying to change sample rate
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink.c: Cannot update rate, monitor source is RUNNING
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-stream-restore.c: Restoring volume for sink input sink-input-by-application-name:MPlayer.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-stream-restore.c: Restoring mute state for sink input sink-input-by-application-name:MPlayer.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-suspend-on-idle.c: Sink alsa_output.pci-0000_00_1b.0.analog-stereo becomes busy.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c: Using resampler 'speex-float-1'
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c: Using float32le as working format.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c: Choosing speex quality setting 1.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] memblockq.c: memblockq requested: maxlength=33554432, tlength=0, base=4, prebuf=0, minreq=1 maxrewind=0
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] memblockq.c: memblockq sanitized: maxlength=33554432, tlength=33554432, base=4, prebuf=0, minreq=4 maxrewind=0
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c: Created input 1 "audio stream" on alsa_output.pci-0000_00_1b.0.analog-stereo with sample spec float32le 2ch 48000Hz and channel map front-left,front-right
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     media.name = "audio stream"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     application.name = "MPlayer"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     native-protocol.peer = "UNIX socket client"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     native-protocol.version = "27"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     application.process.id = "4466"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     application.process.user = "nessita"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     application.process.host = "dali"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     application.process.binary = "mplayer"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     application.language = "C"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     window.x11.display = ":0.0"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     application.process.machine_id = "743db77aa20a2969e7a6baad0000000a"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] sink-input.c:     module-stream-restore.id = "sink-input-by-application-name:MPlayer"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Requested tlength=250.00 ms, minreq=20.00 ms
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Traditional mode enabled, modifying sink usec only for compat with minreq.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Requested latency=210.00 ms, Received latency=371.52 ms
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] memblockq.c: memblockq requested: maxlength=4194304, tlength=158024, base=8, prebuf=150352, minreq=7680 maxrewind=0
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] memblockq.c: memblockq sanitized: maxlength=4194304, tlength=158024, base=8, prebuf=150352, minreq=7680 maxrewind=0
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Final latency 783.04 ms = 371.52 ms + 2*20.00 ms + 371.52 ms
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Latency set to 371.52ms
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: hwbuf_unused=4
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: setting avail_min=444
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Requested volume: 0: 100% 1: 100%
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c:            in dB: 0: 0.00 dB 1: 0.00 dB
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Got hardware volume: 0: 100% 1: 100%
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c:               in dB: 0: 0.00 dB 1: 0.00 dB
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Calculated software volume: 0: 100% 1: 100% (accurate-enough=yes)
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c:                      in dB: 0: 0.00 dB 1: 0.00 dB
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] sink.c: Volume not changing
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] protocol-native.c: Requesting rewind due to end of underrun.
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Requested to rewind 65536 bytes.
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Limited to 65276 bytes.
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: before: 16319
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: after: 16319
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Rewound 65276 bytes.
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] sink.c: Processing rewind...
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] sink.c: latency = 0
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] sink-input.c: Have to rewind 65276 bytes on render memblockq.
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] source.c: Processing rewind...
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-intended-roles.c: Not setting device for stream Peak detect, because already set.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c: Trying to change sample rate
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-stream-restore.c: Restoring mute state for source output source-output-by-application-id:org.PulseAudio.pavucontrol.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] module-suspend-on-idle.c: Sink alsa_output.pci-0000_00_1b.0.analog-stereo becomes busy.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c: Channel matrix:
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c:        I00   I01 
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c:     +------------
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c: O00 | 0.500 0.500
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] remap.c: Using generic matrix remapping
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c: Using resampler 'peaks'
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] resampler.c: Using float32le as working format.
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] memblockq.c: memblockq requested: maxlength=33554432, tlength=0, base=4, prebuf=0, minreq=1 maxrewind=0
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] memblockq.c: memblockq sanitized: maxlength=33554432, tlength=33554432, base=4, prebuf=0, minreq=4 maxrewind=0
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c: Created output 3 "Peak detect" on alsa_output.pci-0000_00_1b.0.analog-stereo.monitor with sample spec float32le 1ch 25Hz and channel map mono
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     media.name = "Peak detect"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.name = "PulseAudio Volume Control"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     native-protocol.peer = "UNIX socket client"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     native-protocol.version = "27"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.id = "org.PulseAudio.pavucontrol"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.icon_name = "audio-card"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.version = "1.0"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.process.id = "4460"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.process.user = "nessita"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.process.host = "dali"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.process.binary = "pavucontrol"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.language = "en_US.UTF-8"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     window.x11.display = ":0.0"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     application.process.machine_id = "743db77aa20a2969e7a6baad0000000a"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] source-output.c:     module-stream-restore.id = "source-output-by-application-id:org.PulseAudio.pavucontrol"
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] memblockq.c: memblockq requested: maxlength=4194304, tlength=0, base=4, prebuf=1, minreq=0 maxrewind=0
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] memblockq.c: memblockq sanitized: maxlength=4194304, tlength=4194304, base=4, prebuf=4, minreq=4 maxrewind=0
Jul 19 12:45:34 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Final latency 731.52 ms = 360.00 ms + 371.52 ms
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Latency set to 371.52ms
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: hwbuf_unused=4
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: setting avail_min=444
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Latency set to 371.52ms
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: hwbuf_unused=4
Jul 19 12:45:34 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: setting avail_min=444
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] protocol-native.c: Underrun on 'audio stream', 0 bytes in queue.
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-source] alsa-source.c: Scheduling delay of 23.49ms, you might want to investigate this to improve latency...
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-source] alsa-source.c: Increasing minimal latency to 2.00 ms
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-source] alsa-source.c: latency set to 20.00ms
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-source] alsa-source.c: hwbuf_unused=62008
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-source] alsa-source.c: setting avail_min=442
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 16 events suppressed
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] protocol-native.c: Requesting rewind due to end of underrun.
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Requested to rewind 65536 bytes.
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Limited to 65276 bytes.
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: before: 16319
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: after: 16319
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Rewound 65276 bytes.
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] sink.c: Processing rewind...
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] sink.c: latency = 0
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] sink-input.c: Have to rewind 65276 bytes on render memblockq.
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] source.c: Processing rewind...
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-source] alsa-source.c: Scheduling delay of 6.33ms, you might want to investigate this to improve latency...
Jul 19 12:45:35 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:45:40  pulseaudio[4457]: last message repeated 8 times
Jul 19 12:45:40 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 15 events suppressed
Jul 19 12:45:40 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:45:42  pulseaudio[4457]: last message repeated 10 times
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Latency set to 371.52ms
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: hwbuf_unused=4
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: setting avail_min=444
Jul 19 12:45:42 dali pulseaudio[4457]: [pulseaudio] source-output.c: Freeing output 3 "Peak detect"
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Latency set to 371.52ms
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: hwbuf_unused=4
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: setting avail_min=444
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Requested volume: 0: 100% 1: 100%
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c:            in dB: 0: 0.00 dB 1: 0.00 dB
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Got hardware volume: 0: 100% 1: 100%
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c:               in dB: 0: 0.00 dB 1: 0.00 dB
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Calculated software volume: 0: 100% 1: 100% (accurate-enough=yes)
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c:                      in dB: 0: 0.00 dB 1: 0.00 dB
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] sink.c: Volume not changing
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Requested to rewind 65536 bytes.
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Limited to 65276 bytes.
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: before: 16319
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: after: 16319
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Rewound 65276 bytes.
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] sink.c: Processing rewind...
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] sink.c: latency = 0
Jul 19 12:45:42 dali pulseaudio[4457]: [alsa-sink] source.c: Processing rewind...
Jul 19 12:45:42 dali pulseaudio[4457]: [pulseaudio] sink-input.c: Freeing input 1 "audio stream"
Jul 19 12:45:42 dali pulseaudio[4457]: [pulseaudio] protocol-native.c: Connection died.
Jul 19 12:45:42 dali pulseaudio[4457]: [pulseaudio] client.c: Freed 4 "MPlayer"
Jul 19 12:45:45 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 15 events suppressed
Jul 19 12:45:45 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:45:46  pulseaudio[4457]: last message repeated 5 times
Jul 19 12:45:46 dali pulseaudio[4457]: [alsa-source] alsa-source.c: Scheduling delay of 9.86ms, you might want to investigate this to improve latency...
Jul 19 12:45:46 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:45:50  pulseaudio[4457]: last message repeated 4 times
Jul 19 12:45:50 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 15 events suppressed
Jul 19 12:45:50 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:45:55  pulseaudio[4457]: last message repeated 10 times
Jul 19 12:45:55 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 15 events suppressed
Jul 19 12:45:55 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:46:00  pulseaudio[4457]: last message repeated 10 times
Jul 19 12:46:00 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 15 events suppressed
Jul 19 12:46:00 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:46:05  pulseaudio[4457]: last message repeated 10 times
Jul 19 12:46:05 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 15 events suppressed
Jul 19 12:46:05 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:46:10  pulseaudio[4457]: last message repeated 10 times
Jul 19 12:46:10 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 15 events suppressed
Jul 19 12:46:10 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:46:15  pulseaudio[4457]: last message repeated 10 times
Jul 19 12:46:15 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 15 events suppressed
Jul 19 12:46:15 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!
Jul 19 12:46:17  pulseaudio[4457]: last message repeated 10 times
Jul 19 12:46:17 dali pulseaudio[4457]: [alsa-source] alsa-source.c: Scheduling delay of 20.03ms, you might want to investigate this to improve latency...
Jul 19 12:46:17 dali pulseaudio[4457]: [alsa-source] alsa-source.c: Increasing minimal latency to 4.00 ms
Jul 19 12:46:17 dali pulseaudio[4457]: [alsa-source] alsa-source.c: latency set to 20.00ms
Jul 19 12:46:17 dali pulseaudio[4457]: [alsa-source] alsa-source.c: hwbuf_unused=62008
Jul 19 12:46:17 dali pulseaudio[4457]: [alsa-source] alsa-source.c: setting avail_min=442
Jul 19 12:46:20 dali pulseaudio[4457]: [alsa-sink] ratelimit.c: 16 events suppressed
Jul 19 12:46:20 dali pulseaudio[4457]: [alsa-sink] alsa-sink.c: Underrun!