I have a 3GS that is almost 2 years old now and had a hard life. It has now developed a tendency to crash when the battery gets below 25%. it will restart using the top button ok but as soon as you put any strain on the battery it crashes when at this low level. When the phone is charged it seams to work fine. I don't think it is related to the most recent firmware as it was doing that before. What do you think this is? I was hoping to hold on to this phone until the new one is out in Summer/Autumn. And don't want to get a 4 with the new one just round the corner Any ideas?