Have you tried removing the battery while the phone is on and waiting at least 30 seconds before putting it back in? That solves most BB problems.
If you are still having problems after that, you can reinstall the software. The link is at the top of this forum http://www.blackberryforums.com/gene...ilanguage.html
However, if the battery pull doesn't work, I might be tempted to wait and see if anyone else has any other answer for you.