Such things do fail. Try another.
I recently installed a pcie esata card to my quad core dell running Vista home premium. I had a WD mybook home connected via esata. It worked immediately after install. It worked for a week or two and now if I reboot and the card is in I get an error message: AHCI bios is not installed..this appears right after Dell splash screen. cannot enter bios from splash screen. If I remove the card windows boots normally.
Update: Flashed BIOS no change