Final Cut Pro won't import clips

I've been working with this file all day and FCP was importing clips just fine. I exported the movie to a Master File, but when I went back to review it, I noticed there was a blip in one of the scenes. So I opened FCP back up to re-import and then re-export the movie, and now it won't import anything. The import dialogue box comes up fine, it lets me select a clip, it even lets me click the Import Clip button, but nothing happens once the dialogue box goes away. What the?