1. Click the 'Start' button and then click 'All Programs.'
2. Click the 'Accessories' tab and then right-click on 'Command Prompt.'

3. Choose the 'Run as administrator' tab from the menu that appears and then enter your administrator password into the field that appears.
4. Type 'sfc /scannow' into the Command Prompt and press the 'Enter' key.
5. Wait for the scan to finish and then restart your computer.