Run System File Checker

System File Checker checks that all Windows files are where they should be and that they're uncorrupted. If you've done all your virus and spyware checking, error checking and defragging, and Windows is still doing strange things, then SFC can avoid a reinstall.
1. Open a Command Window in Administrator mode:

* click Start
* click All Programs, then Accessories
* right click on the Command Prompt option,
* on the drop down menu which appears, click on the Run as Administrator option.



* If you haven’t disabled User Account Control (and you shouldn’t!) you will be asked for authorisation. Click the Continue button if you are the administrator or insert the administrator password.

2. Start the System File Checker

* In the Command Prompt window, type: sfc /scannow,
* press Enter.
* You’ll see “the system scan will begin”.

The scan may take some time and windows will repair/replace any corrupt or missing files. You will be asked to insert your Vista DVD if it’s needed.

Close the Command Prompt Window when the job is finished.

One caveat: you need a Windows CD or DVD to enable SFC to make repairs. Don’t get suckered into buying any Windows computer with a Recovery or Restoration disc