I have an iphone 3gs 16g now for almost 2 years and in the past 2 months it randomly crashes when i am not plugged into a power cord and am using data like on the internet or facebook or the app store. when it started it would only happen when the battery was at 25% and later on at 50% and now it has does it at 90% and i can turn it back on and text and stuff but once i get on the internet or whatever it turns off. and it seems like it drains the battery alot everytime it happens...any ideas? thanks for your time and any sudgestions that you may have 