USB 2 and Gigabyte GA6-BXC motherboard and XP Backup Delay..

I have a Gigabyte GA6-BXC motherboard. I recently installed USB2 PCI
cards that work fine except for my external Acomdata USB removable
drives that use for backup. They backup OK but then fail on verify
with a "Windows XP delayed write failure". I upgraded my bios for the
motherboard from esupport.com but I am still getting the "delayed
write failed" errors with the Windows backup program or with my other
backup program, Retrospect.

Any ideas as to how to correct this?

Thanks.