OK I got the drive and the computer back and looked back through all the suggestions above. I did update the driver to current 2011 version - it was stuck back in 2008. I was really hopeful about that one. Nope, same error 15 minutes after reboot.
Then I did a full repair install of Windows XP. No dice. Same error.
I'm stuck, any more suggestions? The drive is beyond warranty so it would only be exchangeable by Corsair, not Newegg, and not returnable for a refund. Argh!