I had this problem 2 days ago. After hours of reading on the internet, using my old faithful, but slow. laptop, I decided to try the "restore" method. I accessed my laptop's SAFE MODE by tapping F8 while restarting it. I followed the restore instructions and the program listed one program that would be removed. It was AVG 2014. I had just loaded this a few days ago. I continued on and when done, was back to using AVG 2013. Also, I could logon with no problems and didn't lose any other information. Somewhere on the net, I had read that there was a possibility that some recent updates could be causing the logon problem, including AVG. Anyway, it worked for me so thought I would share.