Computer randomly restarts...

Can someone please help me?
Okay for some odd reason, whenever the waiting time to get to the arena (like the countdown thing) gets to 0, my computer would restart. Sometimes it doesnt but most of the times it does. I have no clue whats going on and i was wondering if someone knows what to do.

Thanks a lot if you respond

Roll Back your graphics card drivers if you recently updated them. Otherwise, download new drivers. I had this problem when I installed new drivers on my intel chipset 2 years ago (god that was a horrible computer). The PC would restart randomly. I rolled back the drivers and the problem stopped.