Automatic restart

i was playing a game and i pressed controll+alt+delete. I was going to check something up on the internet. But when i did that it sudently started to freeze a bit and everything got laggy. So i exited the game through controll+alt+delete. And it still was laggy and i tried to open Mozilla Firefox and nothing happend. I got a crash report maybe 2minutes later. And sudently out of nowhere the toolbar went from being windows xp to windows 95 and everything became real slow. So i pressed the turn of button and the computer used 1-2seconds to turn it self off and it usaly uses like 20seconds. When i turned it back on again i got crash report, and i pressed start normaly and the windows xp logo comes up and it starts loading. And sudently the loading freezes and the computer restarts it self. I have pressed F8 and turned of auto restarting but it is still auto-restarting. What am i gonna do please help me.