I can't seem to get class diagrams to work in my visual studio.

If I right click on anything in my project in the solution explorer and choose "View Class Diagram"
I get a message box which says "The class diagram service failed to load"
and another that says "The operation could not be completed. No such interface supported "

From then on, nothing works when I right click on anything in the solution explorer. The menu comes up, but none of the menu options do anything at all.
This happens whether I have a .cd file in the project or not.

Also if I open up a class diagram file, it just gives me a blank page, and there's nothing in the toolbox. At one point it gave me a WebForms type of interface for editing the .cd file.

So anyone have any idea what is wrong with my visual studio? Or what I need to do to fix it?

I'm using VS Standard edition. I had the express editions installed previously, and I uninstalled them before installing Standard.