I got into a situation that when I either shutdown, restart, or logged off, I would hang at the Logging Off screen.
Knowing that the new beta does some security checking during shutdown/logoff I suspected CPF might be the culprit.
I proceeded to exit CPF using the tray icon. When CPF was no longer running (I also killed cmdagent.exe) I did a shutdown and it worked just fine.
After I restarted my system and got into XP I tried a shutdown again with CPF running normally. This time I had no problem.
So it appears CPF did a 'hiccup' on me and that restarting with CPF not running got things back to normal.