Cannot unregister type library xxx - cannot load file, check to make sure it's a valid type library

Question

After editing a previously-working solution, visual studio 2010 will no longer compile the project and is giving me the following error:

Cannot unregister type library {library name} - cannot load file, check to make sure it's a valid type library.

I did quite a bit of searching on the web but there was precious little to be found on this error. What can I do to resolve this error?

Answer 1

I have no idea what caused the error, but it turns out the solution was very easy--just close all instances of Visual Studio and then re-open your solution.