Won't load in Visual Studio 2010 even with preferences setup?

My project has been working with VS2010 for months now, but all of a sudden it won't load scripts from the Editor into VS anymore. I've tried reloading all the relevant pieces, but no luck.

The editor tries to open Visual Studio, but ends up failing and loading Monodevelop instead.

I've checked a few other Answers out, but most people didn't have the same problem as me.