It may help to perform a SFC (System File Checker) scan which will check and fix any corrupted files on your system.
Steps to perform SFC scan:
1. Click the Start button
2. From the Start Menu, Click All programs > Accessories
3. In the Accessories menu, right-click on the Command Prompt option
4. From the drop down menu that appears, select the 'Run as administrator' option
5. Authorize any User Account Control (UAC) elevation request.
6. In the Command Prompt window, type: sfc /scannow (including the space rior to the backslash) and press Enter
7. A message will appear stating that 'The system scan will begin'
8. Be patient because the scan may take some time
9. If any files require replacing SFC will replace them. You may be asked to insert your Vista DVD for this process to continue
10. If everything is okay you should, after the scan, see the following message "Windows resource protection did not find any integrity violations"
11. After the scan has completed, close the command prompt window, restart the computer and check.
Edit to add: A Windows 7 Repair Install may solve the problems. See Brink's tutorial at Repair Install