Windows Movie Maker hates me: Dirge 1, Verse 3

[evewithanapple.livejournal.com]

I just finished making a video on Movie Maker, but when I try to publish it, it tells me that the project contains source files that are missing or have been modified after import. I've gone through every file on the timeline, and they're all there; I haven't moved any of the source files; I nre-imported all the files I used into WMM, just in case; and the torrents I downloaded the clips from haven't been deleted, and I currently have them seeding. Basically, I have no idea what could be causing the problem, but it's making me tear my hair out. Help?