I'm sure you tried opening the file it in another application, but just in case you are not able, can you post the file?

SAT files (ACIS) have versions, and its possible the Carrara importer is not up to date. Its also possible you have a corrupted file.

EDIT, I read your post again, its been a while since I used a Mac, but it sounds like the behavior when a file is not recognized, so maybe the Carrara importer is corrupted.