random freeze of the computer for 10-30 seconds

[Clément]

I have random freeze since update to feisty. I think the kernel 2.6.20 is responsible.
I have a portable Samsung Q35 with intel chipset.
i have often freeze when i watch movies, when i use my hard drive.

Here the logs I have at the time of the freeze :
Jun 13 22:21:29 Navis kernel: [187969.964000] ata1.01: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
Jun 13 22:22:00 Navis kernel: [187969.964000] ata1.01: cmd a0/01:00:00:00:00/00:00:00:00:00/b0 tag 0 cdb 0x25 data 8 in
Jun 13 22:22:00 Navis kernel: [187969.964000] res 40/00:03:00:00:00/00:00:00:00:00/b0 Emask 0x4 (timeout)
Jun 13 22:22:00 Navis kernel: [187976.968000] ata1: port is slow to respond, please be patient (Status 0xd0)
Jun 13 22:22:00 Navis kernel: [187999.984000] ata1: port failed to respond (30 secs, Status 0xd0)
Jun 13 22:22:00 Navis kernel: [187999.984000] ata1: soft resetting port
Jun 13 22:22:00 Navis kernel: [188000.312000] ata1.00: ata_hpa_resize 1: sectors = 234441648, hpa_sectors = 234441648
Jun 13 22:22:00 Navis kernel: [188000.324000] ata1.00: ata_hpa_resize 1: sectors = 234441648, hpa_sectors = 234441648
Jun 13 22:22:00 Navis kernel: [188000.324000] ata1.00: configured for UDMA/33
Jun 13 22:22:00 Navis kernel: [188000.488000] ata1.01: configured for UDMA/33
Jun 13 22:22:00 Navis kernel: [188000.488000] ata1: EH complete
Jun 13 22:22:00 Navis kernel: [188000.504000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
Jun 13 22:22:00 Navis kernel: [188000.512000] sda: Write Protect is off
Jun 13 22:22:00 Navis kernel: [188000.512000] sda: Mode Sense: 00 3a 00 00
Jun 13 22:22:00 Navis kernel: [188000.528000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA
Jun 13 22:22:00 Navis kernel: [188001.060000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
Jun 13 22:22:00 Navis kernel: [188001.068000] sda: Write Protect is off
Jun 13 22:22:00 Navis kernel: [188001.068000] sda: Mode Sense: 00 3a 00 00
Jun 13 22:22:00 Navis kernel: [188001.084000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA