Yes I know to use IDE when installing XP/FLP. Then install drivers make the reg change reboot and change to AHCI. Done it a hundred times
TBH, it has me thinking it was the USB installation for that. But XP failed too (just a different error)
I have not tried slipstreaming the new RST drivers into XP yet. Going to have to figure it out before I bench Spi though. I have one DVDRW left I will try and run that before calling it quits.