I just had this same problem and it was getting on my nerves. I did research on the internet to see if I can pin point the problem and saw that a lot of people was going through it.
I got my problem solved...I went to the T-Mobile store and told them what was wrong and hat I thought was wrong with it. After reading numerous reports about the battery issue, I went out and bought a new battery. Now my Blackberry is working fine
. What a relief. If I was you I will get a new battery. The only downfall to that is I had to pay $40 for a new battery