The version of clr.dll does not match the one mscordacwks.dll was built for

I have a C# console app in Visual Studio 2010 that I can run just fine. When I attempt to run the process in debug mode, I am presented with the following error:

I have tried searching for any information, but I haven't been able to find anything. Can anyone provide clues as to why I can't run this with the debugger?

EDIT: I should clarify that I have been able to successfully debug a console app previously, this is a new situation.

From what I can tell when I'm able to reproduce this error, it is caused by being in the middle of installing Windows updates. So, running updates, then postponing a reboot, then attempting to debug code is what was putting me in this broken state.

I had this issue once and it was caused by an pending Windows Update on the Server where the process was running, which I wanted to attach.