I am also experiencing this bug on Ubuntu Hardy running on SATA disks. Below is an output of the errors (seem to be intermittent - didn't have them for some time and it's occurred twice today, resolved usually by rebooting - apps freeze and am unable to shut down normally):

[  130.366078] ata1.00: exception Emask 0x10 SAct 0x1 SErr 0x400101 action 0x2 frozen
[  130.366084] ata1.00: irq_stat 0x08000000, interface fatal error
[  130.366087] ata1: SError: { RecovData UnrecovData Handshk }
[  130.366094] ata1.00: cmd 61/30:00:87:f6:24/00:00:0f:00:00/40 tag 0 ncq 24576 out
[  130.366095]          res 40/00:04:87:f6:24/00:00:0f:00:00/40 Emask 0x10 (ATA bus error)
[  130.366098] ata1.00: status: { DRDY }
[  130.675177] ata1: soft resetting link
[  130.839834] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[  130.840883] ata1.00: configured for UDMA/133
[  130.840894] ata1: EH complete
[  130.841233] sd 0:0:0:0: [sda] 490234752 512-byte hardware sectors (251000 MB)
[  130.841335] sd 0:0:0:0: [sda] Write Protect is off
[  130.841339] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[  130.860367] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[  149.383870] process `skype' is using obsolete setsockopt SO_BSDCOMPAT
[  199.709149] ata1.00: exception Emask 0x10 SAct 0x1 SErr 0x400101 action 0x2 frozen
[  199.709156] ata1.00: irq_stat 0x08000000, interface fatal error
[  199.709160] ata1: SError: { RecovData UnrecovData Handshk }
[  199.709166] ata1.00: cmd 61/18:00:97:58:a7/00:00:00:00:00/40 tag 0 ncq 12288 out
[  199.709167]          res 40/00:04:97:58:a7/00:00:00:00:00/40 Emask 0x10 (ATA bus error)
[  199.709171] ata1.00: status: { DRDY }
[  200.019966] ata1: soft resetting link
[  200.183626] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[  200.184688] ata1.00: configured for UDMA/133
[  200.184699] ata1: EH complete
[  200.184983] sd 0:0:0:0: [sda] 490234752 512-byte hardware sectors (251000 MB)
[  200.185075] sd 0:0:0:0: [sda] Write Protect is off
[  200.185078] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[  200.185345] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[  200.186162] ata1: limiting SATA link speed to 1.5 Gbps
[  200.186167] ata1.00: exception Emask 0x10 SAct 0x1 SErr 0x400100 action 0x6 frozen
[  200.186171] ata1.00: irq_stat 0x08000000, interface fatal error
[  200.186175] ata1: SError: { UnrecovData Handshk }
[  200.186180] ata1.00: cmd 61/98:00:7f:47:00/00:00:00:00:00/40 tag 0 ncq 77824 out
[  200.186182]          res 40/00:04:7f:47:00/00:00:00:00:00/40 Emask 0x10 (ATA bus error)
[  200.186185] ata1.00: status: { DRDY }
[  200.186192] ata1: hard resetting link
[  205.915454] ata1: port is slow to respond, please be patient (Status 0x80)
[  210.219315] ata1: COMRESET failed (errno=-16)
[  210.219323] ata1: hard resetting link
[  210.537646] ata1: SATA link down (SStatus 0 SControl 310)
[  210.537655] ata1: failed to recover some devices, retrying in 5 secs
[  215.531044] ata1: hard resetting link
[  216.318376] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[  216.319437] ata1.00: configured for UDMA/133
[  216.319452] ata1: exception Emask 0x10 SAct 0x0 SErr 0x0 action 0x9 t4
[  216.319455] ata1: irq_stat 0x00000040, connection status changed
[  216.320538] ata1.00: configured for UDMA/133
[  216.320547] ata1: EH complete
[  216.321360] sd 0:0:0:0: [sda] 490234752 512-byte hardware sectors (251000 MB)
[  216.321482] sd 0:0:0:0: [sda] Write Protect is off
[  216.321485] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[  216.321714] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[  216.321966] sd 0:0:0:0: [sda] 490234752 512-byte hardware sectors (251000 MB)
[  216.322108] sd 0:0:0:0: [sda] Write Protect is off
[  216.322111] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[  216.322366] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA

Below is output of uname -r and lspci:

gmason@lianli:~$ uname -r
2.6.24-19-generic

This also occurs on other machines with similar hardware in the office so I am fairly sure that it's not related to HDD faults etc.

Thanks.

George