unexpected shutdown

[sukhi]

hi this is sukhi frm jabalpur, india
i'm pursuing bachelor of engg. (comp sc, final yr)

i'm facing a problem since last month in vista ultimate
while running in normal mode i experience an enexpected shutdown
event id is 6008 andtask category is none
the power led remains green andthe computer can't b turned on unless u press power button for a while to make power led off

there is no certain time for shutdown sometimes it occurs as soon as u start while sumtimes it can run for more than a hour i'm unable to link this this sutdown with any application

the 2nd thing is there is absolutly no problem like thuis when i'm running vista in safe mode or safe mode with networking

i formated my c drive, instald vista again, changed power settings, scanned with kaspersky..... but nothing worked

one thing more!! probably my cmos is not working bcause every time power goess off from ups or there is a power failure i have to set the bios time again....

this is all i've worked so far...

plz tellme a solution.... is there some hardware problem.....if yes then why it is running well in safe mode