Failed to load source schema when opening BizTalk map

A unit test project in my BizTalk solution caused some problems. When I tried to open certain maps to view them, I would get an error stating the map could not load the source schema, and asking me to select a new schema to replace it. When I clicked yes, I received an error stating Failed to load the source schema, and then no mapper would open up. I was completely unable to view these maps in the designer until I removed the unit test project from my solution.