I forgot to mention that I've been losing BB App World when I do a battery pull. I'd upgrade to the latest OS .442 which is located at the top of this forum. Be SURE to follow the directions exactly.
You can remove the battery by pulling down the back cover of the 9700 (thumbs on both sides at the top of the back cover and slide it down and off - it can be a little stiff going the first time but stay with it as it will come off). When you get the cover off the battery will be right there. Pull it out, wait a minute and then reinstall it. The phone will reboot automatically. Let us know how you make out and if it fixes the problem you're having.