was caused by a screen popping up in connection with Facebook asking me if I wanted to be informed when people unfriended me. If you get that question get out of there as quickly as you can. This has caused me major problems for several days. Apparently a lot of other people had the same problem. I don't know if the question was actually from Facebook, probably not, but it appeared to be from Facebook. Just telling you this to try and save a lot of frustration.