This has now happened for the second time. My system shuts is self off like a power cut and then will not let me boot into windows. It gets to the windows xp user logon password screen and then when I try to access my administrator xp account it does the power off again. I can boot into safemode. There is also possible damage to bios as we had a nightmare trying to reinstall windows as the usb keyboard mouse would not function. Got a new motherboard in end and reinstalled ok. Only for the same problem to occur a few days later after installing progs. I think the most likely source is a bad .exe file. Please help. I can't afford for this to keep happening.