You may try to run System File Checker (SFC scan). The System File Checker tool to determine whether the issue that you are experiencing is caused by one or more system files that are used by Windows Vista, The System File Checker 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:
a. Click Start, and then type cmd in the Start Search box.
b. 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
c. Type “sfc /scannow “without quotes and then press ENTER.