I tried several things now......
diffirent bitrates, non overburning nothing seems to help......
and jet anothet mp3 cd (same brand) works fine........i'm confused

UPDATE:
so after a few hours of testing i came with the following results.....
Some mp3's having this issue with buffering.....but i can't find the reason......
luckely the most mp3's plays and cue's fine, but still want to know what the reason is why some don't.
for the record......i tested all mp3's on both rmp's and the results are on both the same.
I can't afford this problem on a live set with audience.....
Still no reply??