I use mplayer as my media player of choice. If it discovers embedded album art in the media files, it will display them as a popup window. To prevent this from happening you can use the switch -vo null which will tell it to ignore video output. For example.
mplayer -vo null /mnt/SANZA_KEN/PODCASTS/TuxJam_44.ogg
For me using null seemed to to break the terminal output of mplayer.
Replacing null with anything besides the phrase null seemed to fix this issue for me.
Strange the -vo null option is still working for me. That said I also saw that you can use -novideo as well.