Oh and Happy New Year!
Thanks to Surbo at i-hacked.com for most of the work.
DISCLAIMER: I accept no responsibility for any damage you do to your zune. This fix may void your warranty and may cause personal injury if you are not careful. You have been warned.
Step 1: Open Your Zune
If you don't want to the go to the last step for a slower fix.
Ok the sync port has a little piece of plastic around it.
Pull it off very carefully and take out the two screws that are revieled.
Next slide a credit card all the way around the groove in the edge to pop the face off.
Careful the top that you don't snap the headfone jack off the top.
Step 2: Unplug the Battery
VERY CAREFULLY unplug this cable and the screen should go off.
Wait a few mins then plug it back in.
If it asks you to set the date and time make sure you set something like the 1st Dec 2008 else it will lock back up again.
Now Follow the steps in reverse to put the zune back together.
Step 3: Change the Time on Your Pc Too!
If you wish to sync your Zune before the fix is released then stop the auto adjust clock service on your pc then put the time back on there too.
If your zune didn't ask for a new time when you pluged the battery in the you will need to adjust the time this way anyway.
The service is stopped by typing: net stop "windows time" into a command propmt window ( inc quotes)
it is started again by typing: net start "windows time"
Step 4: The Slow Method.
The time it takes to do this will vary depending on how charged it is.
Leave it a further hour after you think it is flat to just make sure.
Then charge it back up and set the time and date to something like 1st Dec 2008 until an patch is released by microsoft.
If you just skipped here from the intro and require PC sync in that time then please read the previous step again else you will end up with the same problem as you had.