I do not claim to have a solution for you, just a couple of troubleshooting suggestions :
1. Run a full virus scan and see if it catches any.
If you do not have Malwarebytes, I would suggest you install a FREE edition and run it. It is the best in the business.
http://www.malwarebytes.org/antimalware/
2. Run a system file check to make sure you do not have corrupt files. It will try to do repair if it finds any.
http://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html
If it tells you it has found corrupt files but unable to repair them, use this method :
In the SAME cmd ( run as admin ) window, copy and paste this command at the flashing prompt....
DISM /Online /Cleanup-Image /RestoreHealth...