Symptom1:

Unable to open the Microsoft Management Console, MMC fails with the message:

“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 Manger

CSLID: FX:{18ea3f92-d6aa-41d9-a205-2023400c8fbb}

Some customers reported after install .NET update, the issue appeared, i.e http://support.microsoft.com/kb/2416473

KB 2486109(http://support.microsoft.com/kb/2486109) was published for this issue.

This problem occurs if the .Net Framework 3.0 feature is not enabled and an update for .net framework 3.5SP1 is installed (which could be through the windows update or through a deployment tool).

If the above steps can not resolve it, use this method:

1. Navigated to the following directory:

C:\Windows\Microsoft.NET\Framework64\v2.0.50727\CONFIG

2. Renamed machine.config to machine.config.old

3. Copy the same file from the working server.

Forum links:

==========

http://social.technet.microsoft.com/Forums/en/winservermanager/thread/6e77f9d0-e86d-4a35-abed-504cf217fc96

http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/b88b12ed-aa1d-428f-a99e-20bb7212e095

http://social.technet.microsoft.com/Forums/en-US/winservermanager/thread/7b9867d2-c8b6-447f-8256-699a309733aa

http://social.technet.microsoft.com/Forums/en/winservermanager/thread/ca91c974-7b35-4f6e-94f0-39ad50e9a562

http://social.technet.microsoft.com/Forums/en-US/winservermanager/thread/07feb5ce-a757-45f8-972e-43c343d946fb

http://social.technet.microsoft.com/Forums/en-US/winserverwsus/thread/f4ff48b7-cc59-4206-84cc-30c17d4d8149

http://social.technet.microsoft.com/Forums/en/w7itproSP/thread/0673911a-685e-41d8-9d6e-d0caa0ae7071

http://social.technet.microsoft.com/Forums/en-US/windowsserver2008r2rds/thread/6752d55e-f4de-4e67-bfbf-ec00d998e8c2

http://social.technet.microsoft.com/Forums/en-CA/winservermanager/thread/746919bc-97a8-4ee3-b9ba-97a4be2d9cc7

http://social.technet.microsoft.com/Forums/en-CA/winservermanager/thread/f60807d3-dfac-42ba-9e9e-f42350ef2f65

A lot of threads found

Symptom 2:

After installing security update http://support.microsoft.com/kb/2449742, the  MMC console opens but when you try to do anything inside you may get error "Microsoft Management Console has stopped working".

The following events are logged:

Event Type: Error
Event Source: Application Error
Event Category: (100)
Event ID: 1000
Date: 14/04/2011
Time: 08:32:53
User: N/A
Computer: cherami.mydomain.local
Description:
Faulting application w3wp.exe, version 7.0.6002.18005, faulting module 49e03238, version mscorwks.dll, fault address 0x2.0.50727.5653.

Event Type: Error
Event Source: .NET Runtime
Event Category: None
Event ID: 1023
Date: 14/04/2011
Time: 08:32:53
User: N/A
Computer: cherami.mydomain.local
Description:
.NET Runtime version 2.0.50727.5653 - Fatal Execution Engine Error (000007FEF21B6D36) (80131506)

Solution:

• If you never installed MS11-028 or have uninstalled it, you should install KB979744-v2 from here or here and then install MS11-028
• If you still have MS11-028 installed, and your Exchange Management tools are currently broken, you should install KB979744-v2 from here or here
•  

Edit: Please refer to http://support.microsoft.com/kb/2540222 for the resolution.