Hi,

 I’d suggest you to do a System File Checker (SFC) scan on your computer. SFC tool scans system files and replaces incorrect versions of the system files by using the correct versions.

To run the System File Checker tool, follow these steps:

1. Click Start, and then type cmd in the Start Search box.
2. Right-click cmd in the Programs list, and then click Run as administrator.

If you are prompted for an administrator password or confirmation, type your password or click Continue

3. At the command prompt, the following line, and then press ENTER:

   sfc /scannow

Check the below link for details:

How to use the System File Checker tool to troubleshoot missing or corrupted system files on Windows Vista or on Windows 7
http://support.microsoft.com/kb/929833

In addition to SFC scan, you may also check your drives for any errors.

You can solve some computer problems by checking a drive or drives for errors. For example, you can check your computer's primary hard disk to fix some performance issues, or you can check an external hard drive if it's not working properly.

Refer the link below for details:

Check a drive for errors
http://windows.microsoft.com/en-US/windows7/Check-a-drive-for-errors

  Please respond back with the status of the issue and let us know if you have any issues.

Azam – Microsoft Support.