Comment 1 for bug 315912

I'm having a very similar problem:

Linux version 2.6.27-9-server (similar to original poster)
Ubuntu 8.10 (x86-64; same as original poster, except for 64 bit vs 32 bit)
16 SATA hard disks (WDC WD1500HLFS-0 Rev: 04.0; different disks to original poster)
SCSI storage controller: Marvell Technology Group Ltd. MV88SX6081 8-port SATA II PCI-X Controller (similar to original poster)
Doing raid5 (same as original poster).
Disabling the write cache (as suggested by original poster) also works for me.

Sample message from the logs:
ata1.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x6 frozen
ata1.00: cmd 61/08:00:3f:75:77/00:00:11:00:00/40 tag 0 ncq 4096 out
         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
ata1.00: status: { DRDY }
ata1: hard resetting link
ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata1.00: max_sectors limited to 256 for NCQ
ata1.00: max_sectors limited to 256 for NCQ
ata1.00: configured for UDMA/133
ata1: EH complete
sd 0:0:0:0: [sdc] 293046768 512-byte hardware sectors (150040 MB)
sd 0:0:0:0: [sdc] Write Protect is off
sd 0:0:0:0: [sdc] Mode Sense: 00 3a 00 00
sd 0:0:0:0: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA