Final Cut Express File Importing Problem

Hello - New Mac user, new here, and questions already! Apologies in advance for my ignorance and complete noobie mystification.

I am using Final Cut Express for the first time, trying to put together clips from several dvd's (to create something of a reel). So, I first used Handbrake to convert the dvds into media files (in mpeg-4 format). I didn't change any of the default settings (including using "same as source" framerate) However, when I try to open/import the files into FCE, I get an "Unsupported Frame Rate" error "FCE does not support this frame rate or the way it is represented."

The manual for FCE mainly focuses of getting media from external cameras, etc., so I can't find anything about importing media files already on my Mac. No doubt I am making this more complicated than necessary. Any suggestions for this process?

Thanks much.