Ouch - I hope you have a recent backup of your data, because it looks like you will need to reload the handheld OS onto the 8300.
Start here ->
How do I wipe the BlackBerry using Jl Cmder? - BlackBerryFAQ
which will wipe out everything on the BB
This may also be helpful ->
How do I upgrade the OS on my BlackBerry? - BlackBerryFAQ