It is 6-Jan and my Zune is finally unfrozen and happily resyncing my glorious music!
Here's what I did:
For about the 10th time I opened the case up and disconnected the battery.
This time, I left the battery disconnected for 2-3 minutes (instead of a few seconds).
As soon as I reconnected the battery, I flipped the Zune over and hit BACK+CENTER+RIGHT buttons. I did this as the white horizontal line was building across the bottom of the screen.
This time instead of freezing

like it has every other time I tried something...it opened the the correct screen showing Music, Video, Podcasts, radio...etc.
Then I close dthe case up, connected the screws, plugged it in to my PC and my data started resyncing.
I don't know if this will work for everyone who is still haveing the frozen-zune problem, but it worked for me.
I almost think that there might be several different fixes that might work on different Zunes - anything to jar the boot process past the infinit loop it encounters when calculating the date.
Good luck