I would go with a clean install. Make sure you save your file to some other location, and zap this one. New install, patch to match Steve, copy your save game back to the new install, open save, click yes when you get the PWX error, run a few changes. Save.
Then follow withqs's advice & run a test setup & send it back & forth to make sure your platform is stable. Once it is, you can proceed to mayhem.
If it ain't broke, don't fix it!