I've actually had something really similar happen to me on my PC. Random music would play from a source I couldn't find the process for, it'd do random things like repeat at certain spots or start a new song randomly, and sometimes it was like a talkshow kinda deal. I thought maybe my computer was picking up radio signals or something. I stopped having the problem after doing a virus/spyware cleanup but I don't know how this would help you on a blackberry. It creeped the hell out of me when it happened on my PC. The way you describe it is pretty much exactly the kind of thing that happened
