Yep, although I like using linux, here's another windows related techie article.
On one of the DCs at work, I'd noticed errors on startup for the windows Server Manager window, but not really looked into it, as I'd not needed to use it for anything.
Today while trying to update the xen server tools on it, they wouldn't run, so I tried to open event viewer, only to get a nice error saying that:
MMC could not create the snap-in.
Name: Event Viewer
CLSID: FX:{b05566ad-fe9c-7a4cbb7cb510}
A quick google showed a few people with the same problem, with various suggestions, including using windows feature control to remove .net framework. This wasnt an option, as this also was having the same problem of loading up. However, a bit more looking around, and on the microsoft social.technet I found the suggestion to reset the machine.config file to defaults in C:\Windows\Microsoft.NET\Framework64\v2.0.50727\CONFIG\ I did this by renaming machine.config to machine.config.old, then copying machine.config.default to machine.config.
There was no need to reboot, as the event viewer mmc opened up without problems. The xen tools install I was trying to do also worked fine, so I wonder if both problems were related