I have the same problem with ubuntu feisty (the previous ubuntu version suffers also from this problem) on an Acer Aspire 9410. 
Dmesg says:
[26622.024000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[26622.024000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
[26622.024000] sda: Write Protect is off
[26622.024000] sda: Mode Sense: 00 3a 00 00
[26622.024000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[26855.108000] ata1.01: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
[26855.108000] ata1.01: cmd a0/01:00:00:00:00/00:00:00:00:00/b0 tag 0 cdb 0x25 data 8 in
[26855.108000]          res 40/00:03:00:00:00/00:00:00:00:00/b0 Emask 0x4 (timeout)
[26862.108000] ata1: port is slow to respond, please be patient (Status 0xd0)
[26885.124000] ata1: port failed to respond (30 secs, Status 0xd0)
[26885.124000] ata1: soft resetting port
[26885.820000] ata1.00: ata_hpa_resize 1: sectors = 234441648, hpa_sectors = 234441648
[26885.828000] ata1.00: ata_hpa_resize 1: sectors = 234441648, hpa_sectors = 234441648
[26885.828000] ata1.00: configured for UDMA/100
[26886.016000] ata1.01: configured for UDMA/25
[26886.016000] ata1: EH complete
[26886.032000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
[26886.048000] sda: Write Protect is off
[26886.048000] sda: Mode Sense: 00 3a 00 00
[26886.064000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[26886.096000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
[26886.112000] sda: Write Protect is off
[26886.112000] sda: Mode Sense: 00 3a 00 00
[26886.144000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[27268.136000] ata1.01: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
[27268.136000] ata1.01: cmd a0/01:00:00:00:00/00:00:00:00:00/b0 tag 0 cdb 0x25 data 8 in
[27268.136000]          res 40/00:03:00:00:00/00:00:00:00:00/b0 Emask 0x4 (timeout)
[27275.136000] ata1: port is slow to respond, please be patient (Status 0xd0)
[27298.152000] ata1: port failed to respond (30 secs, Status 0xd0)
[27298.152000] ata1: soft resetting port
[27298.848000] ata1.00: ata_hpa_resize 1: sectors = 234441648, hpa_sectors = 234441648
[27298.856000] ata1.00: ata_hpa_resize 1: sectors = 234441648, hpa_sectors = 234441648
[27298.856000] ata1.00: configured for UDMA/100
[27299.044000] ata1.01: configured for UDMA/25
[27299.044000] ata1: EH complete
[27299.060000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
[27299.076000] sda: Write Protect is off
[27299.076000] sda: Mode Sense: 00 3a 00 00
[27299.100000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[27299.132000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
[27299.148000] sda: Write Protect is off
[27299.148000] sda: Mode Sense: 00 3a 00 00
[27299.172000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[27439.180000] ata1.01: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
[27439.180000] ata1.01: cmd a0/01:00:00:00:00/00:00:00:00:00/b0 tag 0 cdb 0x25 data 8 in
[27439.180000]          res 40/00:03:00:00:00/00:00:00:00:00/b0 Emask 0x4 (timeout)
[27446.180000] ata1: port is slow to respond, please be patient (Status 0xd0)
[27469.196000] ata1: port failed to respond (30 secs, Status 0xd0)
[27469.196000] ata1: soft resetting port
[27469.904000] ata1.00: ata_hpa_resize 1: sectors = 234441648, hpa_sectors = 234441648
[27469.912000] ata1.00: ata_hpa_resize 1: sectors = 234441648, hpa_sectors = 234441648
[27469.912000] ata1.00: configured for UDMA/100
[27470.096000] ata1.01: configured for UDMA/25
[27470.096000] ata1: EH complete
[27470.112000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
[27470.132000] sda: Write Protect is off
[27470.132000] sda: Mode Sense: 00 3a 00 00
[27470.148000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[27470.164000] SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
[27470.164000] sda: Write Protect is off
[27470.164000] sda: Mode Sense: 00 3a 00 00
[27470.200000] SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO or FUA