stuck on "save directory not valid"

I downloaded 2.8.5 a week or so ago and it had been running fine. Then this week when I tried to start it up I got the following message:

Your save directory is not valid. It may have been deleted, you may not have permissions to write to it, or there may be another problem. Please choose a different directory.

So I choose a different directory and no matter what the directory it won't accept it when I hit the "select" button! My directory had not been deleted, my permissions did not change. The worst thing is that it won't accept "cancel" and so I can't even shut it down! It just asks for a new directory and then won't accept any directory! I even did a reinstall. What is wrong?!