Suggestions only :
1. If this problem is recent, and if you remember a "good" date when you did NOT have this problem, then do a system restore.
Pick the good date as your restore point.
http://www.howtogeek.com/howto/windows-vista/using-windows-vista-system-restore/
2. If system restore does not bring it back to normal, so some "troubleshootings ".....
a.) Run a full virus scan to make sure your computer is clean. I recommend that you use Malwarebytes to do the work. It is the best for such a job.
If you don't have it, here is the download link. Pick the FREE edition.
http://www.malwarebytes.org/products/malwarebytes_free/
If it catches anything, get rid of the virus and see if your computer is ok now.
b.) Run a system file check to look for corrupt files. It will try to do repair if any corrupt files are found.
http://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html
When file check is finished, it will give you a summarized report of one of the followings:
(paraphrasing)
No integrity violation found.
Found corrupt files and repair successfully.
Found corrupt files but unable to repair.
If it has done the repair successfully, see if your problem is gone.