Visual Studio doesn't like slackers. If you don't use it for a while, it may decide to throw fits - in this case it's this indecipherable message:
It either coughed up the message when I tried to create a new project, or plain bombed out if trying to open an existing one. Turns out it's basically a stale cache of some sort. Just get rid of the ComponentModelCache folder it'll be back happy again.