Apparently Rational Rose changes their file formats between minor versions. Because of this I just had to re-do a large amount of work.
This whole program is a piece of crap. Their UI is terrible, inconsistent, and feels like it was built for Windows 3.1. For example, how do you delete something from a model? The 'delete' key you say? Of course not! You use ^D! Did you make a change you didn't like? Would you like to undo it? Sorry! You can't! Delete the object and then add it again.