Comment 3 for bug 537596

I don't think this is a duplicate. Even though the main symptoms are the same, this bug was introduced newly by some update in Lucid after the alpha release. Also the other bug report is about GDM, which has since been completely rewritten.

After investigateing this some more, I noticed that when the system is in the "broken state", the attributes of some devices are different. Listing of ls -la /dev/dvb/adapter0/ in normal state:
drwxr-xr-x 2 root root 140 2010-03-14 08:20 .
drwxr-xr-x 3 root root 60 2010-03-14 08:20 ..
crw-rw----+ 1 root video 212, 4 2010-03-14 08:20 ca0
crw-rw----+ 1 root video 212, 0 2010-03-14 08:20 demux0
crw-rw----+ 1 root video 212, 1 2010-03-14 08:20 dvr0
crw-rw----+ 1 root video 212, 3 2010-03-14 08:20 frontend0
crw-rw----+ 1 root video 212, 2 2010-03-14 08:20 net0

Listing in "broken state":
drwxr-xr-x 2 root root 140 2010-03-13 14:38 .
drwxr-xr-x 3 root root 60 2010-03-13 14:38 ..
crw-rw---- 1 root video 212, 4 2010-03-13 14:38 ca0
crw-rw---- 1 root video 212, 0 2010-03-13 14:38 demux0
crw-rw---- 1 root video 212, 1 2010-03-13 14:38 dvr0
crw-rw---- 1 root video 212, 3 2010-03-13 14:38 frontend0
crw-rw---- 1 root video 212, 2 2010-03-13 14:38 net0

The plus sign is missing. According to "info coreutils 'ls invocation'":

     A file with any other combination of alternate access methods is
     marked with a `+' character.

Maybe the bug is related to something in policykit or apparmor?