Have you tried 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 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.
If no joy, your next step would sensibly be a repair install. However, you could first try Jesper's code to see if it will work on Windows 7:
Run this command from an elevated command to create the SC:
sc create wscsvc type= share start= delayed-auto error= normal binPath=
"C:\Windows\System32\svchost.exe -k LocalServiceNetworkRestricted" depend=
RpcSc/WinMgmt obj= "NT AUTHORITY\LocalService" DisplayName= "Security Center"
From Jesper's post, this should provide the right security descriptor:
sc sdset wscsvc
D:(A;;CCLCSWRPWPDTLOCRRC;;;SY)(A;;CCDCLCSWRPWPDTLO CRSDRCWDWO;;;BA)(A;;CCLCSWRPLOCRRC;;;IU)(A;;CCLCSW LOCRRC;;;SU)(A;;CR;;;AU)(A;;CCLCRP;;;S-1-5-80-2006800713-1441093265-249754844-3404434343-1444102779)S:(AU;FA;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;W D)
(Note: I've disabled smilies in this response so Jesper's code is properly displayed.)