If it were me, I would use the SEARCH
feature or read the FAQ to find a solution quickly. What should I do with App Error 523? - BlackBerryFAQ
Most likely you need to wipe the device with Jl_cmdr and reload the OS.
See the FAQ for Jl_cmdr instructions and the yellow sticky at the top of the 8300 for the latest OS for your device and instructions. The OS is device specific, meaning it has to be an 8330 OS. Follow the directions EXACTLY and be patient. It can take an hour or longer.