I have installed Foobar2000 in Playonlinux (ElementaryOS) and all it can play are radio internet streams.
All files give the error
Unable to open item for playback (Unsupported file format): - even common formats like mp3.
Along Foobar2000 I also installed Winamp to see if that works: yes, it does.
I have Foobar installed in a similar manner in another Linux installed in multiple boot (in Mint 17.2 KDE) and there it all works fine.
How could I investigate what is different between the two systems?