I'm hoping third time's the charm for me here. I thought I'd fixed it twice, but so far, after two hours, a restart, and multiple zoning tests it seems to be working now. I installed the AC3filter pack (I believe someone else mentioned this as well), rebooted the computer, and, knock-on-wood, the radio (and regular game music) is behaving just fine. The only oddness I've found is a bit of a odd corruption on the spoken radio bits, but only for the first few seconds.
If anyone wants to try the filter pack, here's the link. I installed the http://ac3filter.net/projects/ac3filter/releases (it's free.)
having the same problem here..i went ahead and tried some of the workarounds here but nothing seems to work. Radio announcer still announces, but no music plays. However this problem is isolated to the PIp boy Radio...every other radio i encounter works fine and plays music.