back up your apps using titanium back up, or some other back up utility... then do a factory data reset in ClockWork.... that MIGHT do the trick... if you're having issues with force closing I wouldn't restore the ystem data in titanium I'd only do the APPs...
If that doesn't do it you should be able to just reflash the Rom or another rom that is appropreiate for your boot loader version.. If you're wanting to go back to stock the best and most sure fire way is NVflash... there's stickies in the techincal section on the process...