hang for no reason..

hi

im using winXP pro SP1.

the problem is that sometimes,only every 10 restarts the system freezes completely,nothing works not even the mouse.
pressing ctrl/alt/del instead of device manager i get a dead
black monitor screen and after this i can only push the pc`s reset button.

when it starts again everything is normal and working ,no error message or anything to say about system failure etc...

this can happen only 3-4 times every month and started about 2 months ago.

does somebody has an idea what can cause this? is it software related or do i have to downclock it a bit?
its P4 HT at 3GHz and its running at 3.52 GHz.

regards.
sk

Could it be that heat is locking up your machine, I see that it's overclocked. Also check your powersupply it may be on it's way out. When systems just lock up its usually heat, memory, or power issues. At least the expirences that I have had.