Repair WMI on Windows 7

To fully rebuild the WMI Repository follow these steps:

1. Disable and stop the winmgmt service.
2. Remove or rename C:\Windows\System32\wbem\repository.
3. Enable and start the winmgmt service.
4. Open a cmd prompt as Administrator.
5. In the cmd prompt navigate to C:\Windows\System32\wbem\
6. Run the command for /f %s in ('dir /b *.mof') do mofcomp %s This will take a minute or so to complete.
7. Run the command for /f %s in ('dir /b en-us\*.mfl') do mofcomp en-us\%s

If its a file level corruption you could probably try the sfc /scannow command - this will check and replace any system files that are damaged.

I had the same problem and using Repair WMI from Tweaking.com fixed it.