When playing Ogg Vorbis on my portable player, many Ogg Vorbis files were skipped or crashed the system. Since the firmware is the latest available, I couldn't sit still and investigated the problem, which is:

It seems that Foobar2000 creates malformed Ogg tags - there is a massive amount of junk bytes between the tag and the actual music data (00 bytes).

See the difference between a normal tag and the one created by Foobar2000 0.9.4.3:

Malformed tag

Normal tag

I think it has to do something with the comment tag, without it fb2k is able to tag files normally. I can upload the the sample files if needed.