Ok, I’m at a loss. I did Edit>Purge to no avail. Went into Preferences>Cache, and hit “Clean Database & Cache” under Conformed Media Cache. Also temporarily moved all the files from the listed disk cache location, since that folder seems to be shared among other applications. Rebooted the computer, and nothing. I’m running CS5.5 for what it’s worth.
I’ve tried making a brand new composition, copying and pasting from the old comp. No luck. I’ll try completely re-importing the clips into AE, but I’d love to figure out what’s going on here.