There is no way that a virus can hide inside an MP3 file and infect you when listened to. I am not sure how else to say that :)

The MP3 file does not contain any executable code by it's nature. No MP3 application monitors the MP3 stream for executable code. Your PC will not execute a file with a .mp3 extension under any circumstances.

One page of info ... F-Secure Hoax Information Pages MP3 Virus

Now, it IS possible for someone to convince you to execute a file you THOUGHT was an MP3 file. Maybe by sending you a email attachment with a .mp3 extension and a hidden .vbs extension or so on. Or by sending you an .exe and telling you that it would play a song.

But an MP3 file simple is not a possible carrier.

I could take an infected .exe, rename it as .mp3 and your virus scanner would pick it up as infected, but it isn't an actual MP3 file and not only wouldn't it play but it couldn't infect you unless you named it back.

I don't mean to sound all techie on this .. but this is how rumors get started.