Had to move this to the appropriate forum, so hopefully you get better help here.
I'll ask the guy on my team that tests this and see if he has any suggestions. I'm guessing you have turned the xbox on and off? Maybe try renaming the playlist? Disable and reenable sharing on the Zune software, and on the Xbox itself?
Sorry, this isn't my area of expertise, just throwing some ideas out there.
Matt Akers
Zune Product Team
.: This posting is provided "as-is" with no warranties, and confers no rights :.