Windows not running as it should.
Maybe you should run the system file checker for your windows installation.
It will see whether any system files have been modified or corrected.
Click start , then run and enter cmd and a dos box will open , then type sfc/scannow
This will scan your windows installation and may ask you for your windows disk so you can repair it – Just insert your disk when you are asked for it and let it run.
Remember follow the instructions on the screen
Here is the Microsoft Support Note on the System File Checker for Windows