How to Fix a Corrupt System File

1. Click the 'Start' button in the lower left corner of the Windows desktop.
2. Type the string 'CMD' into the 'Run' dialog box. This will initiate a command prompt window to appear.
3. Type the string 'SFC /scannow' (without quotes) into the command prompt. This will initialize the Windows file protection utility that checks all system files against their original versions, sizes and modification dates. If a system file is found to be changed or corrupt it will immediately be replaced with a valid original version.