According to Herman at gizmodo, this is the solution:
"Your zune will need a "hard reset."
To do this, use a small screwdriver to pop off the plastic shielding where the zune cable plugs into and remove the two screws on either side of the plug. Next pop the cover off and locate the battery plug at the top left corner of the zune, using your screw driver, pop the cable connection half way off, and do this to the other plug on the right side. Wait 3 seconds, then push down the right connector and then the left battery connecter. Your zune should start up immediately. Press the backing of the zune down (make sure headphone jack is aligned) and put the screws and cover back in place.
It's an easy process but if you're unsure don't attempt it if you think you'll screw it or something. :)"
Not pretty, but it might help those of you who have this problem.
According to others on the forum, it is caused by the new firmware, so you might not want to update it. Changing the clock might be a temporary fix if you want the new firmware.