Hp pavillion dv3 2111TX freeze when unplug charger

Hello,currently now im using hp pavillion dv3-2111TX, i buy last year and the original window get is Vista home premium ( dont have any prob ), after tired using vista im switch to window 7 ultimate 32 bits, and im realize that my laptop keep freezing about 5 minute after i unplug charger.. than it become normal after 5 minute. im try to restart and the result is im must waiting also coz its sill freeze and hang.. huh what should i do.. help2...