Hi Chris and Falcon !! Welcome to the forums
@ Falcon : Nice suggestions
@ Chris : Is it the situation from the very beginning , or a recent scenario ? If recent , have you ran any third party disk cum registry cleaner before getting into this trouble ?
Initially yo may try one thing , that is SFC /SCANNOW Command - System File Checker
. It will bring everything to system default .
If SFC scan failed , it is to try a System Restore
with a previous date before the trouble came . And if System restore is also failed , finally it is to try a Repair Install
Please post back the results .