Laptop switches off

I've had my laptop for about 6months and use it daily. recently i've been experiencing a problem; at random times my fans will cut off my msn will freeze & if im watching something it will freeze for a few seconds, then a window will show for about 5 seconds which says:- " The exception Illegal Instruction. An attempt was made to execute an illegal instruction( 0xc000001d) occured in the application at location 0x63590940. Click on Ok terminate the program. " After which my laptop will shut off. please someone help me with this im on windows xp.