Thanks, but I am not sure. I could try again with another one.
But I still wonder why all the same hardware work fine under Win2000+sp4, while so unstable under WinXP+sp1 (I also tried to disable the autobatically reboot option as someone said, but the system went to blue screen of death this time, damn it!)?
BTW: the BIOS of the motherboard had been flashed to V1.0d of 07/2003. The WinXP+sp1 has been claimed to be valid (copyright) when I went to microsoft's website for update.