mp3 files with vbr (variable bitrate) "cropped"

Hi gurus,

my mp3 files with variable bitrate stop too early - looks as if xbmc does not read / calculate the duration correctly for vbr files.
This problem only occurs with xbmc 12 frodo, everything works fine with xbmc 11 eden.
My platform is ubuntu 12.04.

Any ideas how to fix this?

Thanks!