Granix

recently my 3-years-old computer got a big problem,when i used to get in to Windows XP desktop,it just hang it right there,then it will auto restart.it happen almost very time i start my computer.so with some common sense,i thaught that it is time for a format and reinstall XP,but strange phenomena still happen,it hang again whenever i start my newly installed XP,but now with some hint,its reported i had a XP SP2 bug in my computer,but problem is,how the hell this bug came in my computer as i havn't even online after my reinstall and didn't updated my XP since last year?is it true that this bug is the main factor to my computer problem?what should i do?please help.....