IRQL_NOT_LESS_OR_EQUAL showing on BLUE SCREEN

Hi ,

My DELL laptop Core-2-duo 1GB RAM / 120GB HDD / Windows VISTA, but i remove it and install Win XP 4 month ago..I have 3 partition in my HDD other than C/

Yesterday, suddenly its started rebooting automatically... Also i did not install any sftwr or any hardwr in it yesterday..I can't even get in safemode, last known confi. and normal mode.. every time it again rebooting by itself.. this is the first time i encountered with this kind of problem..

whn I disable restart mode it shows

QUOTE
A problem has been detected and windows has been shut down to prevent further damage to your computer .

IRQL_NOT_LESS_OR_EQUAL

(blah blah blah ... )

Technical Information:

*** STOP: 0x0000000A (0x00000000, 0x0000001C, 0x00000001, 0x804FAD30)


I tried every thing but it is not wrking

Anybody knows how to solve it ? (Other than formatting ...)

Please