Game Gear PRoblems

Hey guyz and gals, would be very happy if someone knew wots wrong with my Game Gear.......heres the problem: when i turn it on, i play for about 3 mins maybe a little more and then the screen goes completely white and the Game Gear turns itself off
i have tried using all 15 of my games and using new batteries and even an AC adapter so plz can someone let me know wots wrong????