Porky, could you tell me which tracks are the ones causing trouble?
I think I know what the problem is...
I've edited most of the files (fading them out in the end, removing unwanted ambient sounds at the beginning and stuff like that), so I re-compressed them to MP3 afterwards. But some files were fine the way the were on the MI4-CDs (so I didn't edit and re-compress them)... my guess is, that their compression isn't standard-MP3, and so they are causing trouble with some players.
So, I'm gonna re-compress an re-upload them.