I had a weird problem after running Windows updates on a Windows Server 2008 machine. The Server Manager would not start and it displayed a weird MMC error. I couldn’t even add the MMC snap-in manually. But I found a solution.
1. Navigate to the following directory:
2. Copy the ‘machine.config’ file to desktop just in case before you go to 3rd step.
3. Rename machine.config to machine.config.old which is locating in the directory above.
That’s it, nothing else is needed. Try running Server Manager now and all will be good again in your world!