I do not think it is possible to insert a virus in a mp3, although I did find some weird mp3 wich were playable, but, to burn them as an audio track you had to convert them to a wav file (nero=unrecognised format, adaptec=copyright something...) And another kind of weird mp3 was playable fully but if I tried to edit it with nero wav editor I could only edit the first minute or so...

I doubt that any program that cannot load a file would try to rename it into a .com or .exe and run them.. it would just be looking for trouble...