See
Is your BlackBerry Nuked? - BlackBerryFAQ.
Another option is to try and boot in safe mode. See
KB17877-How to start a BlackBerry smartphone in safe mode.
Either way, try and delete the app that is causing the problem.
If you boot up in safe mode you can do a full backup. That will be a good idea because you could end up deciding to wipe the device.
If you decide to wipe, see the two articles at the FAQ re JL_CMDER.
Posted via BlackBerryForums.com Mobile