I am using 32bit windows 2008 server as AD domain controller . After upgrading dot net framework ,all mmc snap-ins were failing to open .
All tools like Server Manager , Event Viewer were showing an error message like..
MMC could not create the snap-in
MMC could not create the snap-in. The snap-in might not have been installed correctly.
Name: Server Manager
Finally I came to know that it is due to .netframework and it can be fixed by removing .net 3.5 or renaming machine.config file in .netframework 2.x CONFIG directory .
First I ran sfc /scannow then renamed C:\Windows\Microsoft.NET\Framework\v2.0.50727\CONFIG\machine.config to machine.config.old
After rebooting the server everything worked fine.
You may try to remove .net 3.5 SP1 if you dont want to rename machine.config in .netframe work 2.x directory .