[CentOS] Disk errors on CentOS 5 - libata bug?

I just installed CentOS 5 on a computer. On boot, I get the a error message,
related to 2 SATA disks. These errors did NOT appear on version 4.4 with the
EXACT same hardware.

Despite the error messages, the disks seem to be working with no problems.

Could someone please tell me what these error are and if there is some known
way to prevent them?

I searched the Net for these errors and they seem to appear with a wide 
range of disks,
controlers and chips set brands, even with different Linux distributions. 
The issue seems to
be related to the last few kernel versions and is perhaps a bug or ill 
implemented "feature" of libata.

My configuration:

- 2 Hitachi SATA 120 GB Harddisks (first generation, no NCQ)
- Intel P4 3GHz
- Tyan Tomcat i875p motherboard, Intel ICH5 disk controler
- 1 GB ECC RAM
- 2 Intel Gb NICs
- 1 Intel 10/100 NIC

Error message follows:

---------------------------------------------------------------------
ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata1.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata1: EH complete
ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata1.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata1: EH complete
ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata1.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata1: EH complete
ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata1.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata1: EH complete
ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata1.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata1: EH complete
ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata1.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata1: EH complete
SCSI device sda: 241254720 512-byte hdwr sectors (123522 MB)
sda: Write Protect is off
sda: Mode Sense: 00 3a 00 00
SCSI device sda: drive cache: write back
SCSI device sda: 241254720 512-byte hdwr sectors (123522 MB)
sda: Write Protect is off
sda: Mode Sense: 00 3a 00 00
SCSI device sda: drive cache: write back
ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata2.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata2: EH complete
ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata2.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata2: EH complete
ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata2.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata2: EH complete
ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata2.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata2: EH complete
ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata2.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata2: EH complete
ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata2.00: tag 0 cmd 0xb0 Emask 0x1 stat 0x51 err 0x4 (device error)
ata2: EH complete
SCSI device sdb: 241254720 512-byte hdwr sectors (123522 MB)
sdb: Write Protect is off
sdb: Mode Sense: 00 3a 00 00
SCSI device sdb: drive cache: write back
SCSI device sdb: 241254720 512-byte hdwr sectors (123522 MB)
sdb: Write Protect is off
sdb: Mode Sense: 00 3a 00 00
SCSI device sdb: drive cache: write back
---------------------------------------------------------------------

Thank you
Miguel