What happens if you actually disconnect the audio interface and open that particular project, just to see if it will open this way?
If it DOES open without the audio interface connected, it will yell at you for no audio device but should still open. That would at least allow you to examine the project more closely, or even try doing a Save As to save it off under a different name, in case there is some sort of project corruption - no guarantees, but at least you would have something to try, and should be able to get into the project if there are any issues between that project and the audio interface. IF you try a Save As, plug the interface back in and try opening up the newly-saved version of the project, and see what happens.
Bob Bone