The program stops when I try to open a file

[djargad]

I encoded my first movie with .ogg sound.As a result I got an .ogm file
which works just fine in BSPlayer.

So the only thought that comes to my mind about the problem is that
it's an audio problem.And i say that because all of my previous movies have MP3 sound.

So the solution could be to the MP3 codec.Could somebody tell me what excactly do i hava to install so that things work fine(i hope)?