Uncaught exceptions are tough to diagnose. they are typically caused by a corrupt file or incompatible app or theme. What did you do with the device just before this error began to occur?
Do a Google search on your specific error code "uncaught exception 4>=4" and see what you find. This is the first that popped up when I did it: Error Msg (Uncaught exception: index 4>=4) - BlackBerry Support Community Forums
You will probably find that you need to wipe the device and reload the OS.
Try a battery pull and see if that has any effect.