Which version of PF? I had one that started to issue a prompt every time I launched it. It wanted to know if I wanted it copied over to the user Application folder (which it already was in). You can say yes or no to that. If no, it asks again next time. If yes, it hangs. You can turn off the prompt too.
You might have hit some combination of this. The prompt to move the app is really bizarre and should just be dropped IMO.