HELP with my xbox 360!?

ok so i have this really weird problem that happened to me yesterday. while i was playing Halo on xbox live, right before i got into a game, my xbox froze and i had to restart it. i went to play again and the same thing happened. this time when i restarted it, i got the three red rings. i left it alone for a while and i tried it again and all was well. i tried playing another game and i wasn't even IN multiplayer and it froze again. now, anytime i play a game, five minutes into it, it freezes. any suggestions?