If you ripped the files as VBR with Musicmatch (or something else that uses the FhG encoder), it will output a VBRI header, rather than a Xing header.

MP3T/S can screw up slightly and output a malformed frame containing the Xing header and the VBRI header. This causes emplode to barf on that file.

I've forwarded some relevant information to the author of MP3T/S, and he's looking/looked at it. I haven't heard since, though.

If this doesn't sound like your problem, then I suggest that you contact me privately, and we'll discuss how to get one of the broken files to me, and I'll take a look at it.