I have 2 servers with Windows Server 2008 Standard R2 SP1 and, after installing Microsoft updates, I started to get the error described in the title of this message. Such a problem occurs when trying to run Event Viewer and Server Manager. I searched in Google and found this link (http://blogs.technet.com/b/askperf/archive/2012/08/10/mmc-has-detected-an-error-in-a-snap-in-and-will-unload-it.aspx
) but it did not fix my situation. I have not found any other real answer to this issue. I am attaching an image of the error of one of the servers for your review, I would like to work for a solution for one server first and consider the other one separately in case the solution does not solve the second one because it seems that the Microsoft updates that caused this problem are not the same in both servers.