When you boot in Windows XP in Safe Mode - can you run a thermal monitor to see if any heat issues are present?
You might want to run a stress test like Prime95 for a few hours and monitor the temps as well.
If it isn't thermal related, I my best guess would indicate the possibility of issues with the SATA controller on the mobo.
Another possibility - could the DVD drive be failing? Have you tried an install from USB stick?