Had this same problem as well...
ZERO success in finding solution online, so I figured I'd come to Zune.net and contact Support, didn't realize there were forums here!
I have a pretty decent system:
Core 2 Duo 2.0Ghz... 3GB RAM.
I knew this was most likely a Zune issue, because Windows Media Player was fine. Even updated audio drivers... naturally, no fix.
Disabling the Video Enhancements instantly solve my problem!