Reset the security center:
1. Go to control panel and open Administrative tools.
2. Click on services.
3. Go down to Windows Management Instrumentation.
4. Stop this service. Stop Security Center service too. Set them to Automatically start.
5. Exit out of this area, to your desktop.
6. Right click Start, and choose Explore.
7. Go to c:\windows\system32\wbem\repository. Delete this subdirectory ONLY. Leave the others there.
8. Exit back to your desktop and reboot your computer (you might need to boot twice).