Patch 1.1 only addresses server issues. They go so far as to say that if you aren't running a server, there's no need to download the patch at all. You can play on a 1.1 server with your 1.0 game.
As for your particular problem, I doubt it's patch related. At least, I haven't heard this issue come up in regard to it. I did find a similar thread on the Tech Issues forum (Search engine? We don't need no stinkin' search engine!) No one had a definite answer, but the consensus seemed to be that a mod must've changed some character information. Look at your stats in-game - do you have "0 missions completed?" If so, there's your problem.
Sadly, the thread didn't provide any kind of fix, either. You might spend some more time sifting through old threads for an answer, I only provide a path.
I just punched "experience" into the search engine and limited the search to the technical issues forum, btw.