Microsoft have responded to the spate of Zune 30 crashes, blaming a bug in the PMP's code that leaves it unable to cope with the leap year. Since the problem will apparently reset itself on January 1st 2009, at noon GMT, the company is not planning an immediate fix; instead, users should follow instructions at the Zune forums which basically amount to letting the PMP's battery expire and then restarting it.
"Early this morning we were alerted by our customers that there was a widespread issue affecting our 2006 model Zune 30GB devices (a large number of which are still actively being used). The technical team jumped on the problem immediately and isolated the issue: a bug in the internal clock driver related to the way the device handles a leap year. The issue should be resolved over the next 24 hours as the time change moves to January 1, 2009. We expect the internal clock on the Zune 30GB devices will automatically reset tomorrow (noon, GMT). By tomorrow you should allow the battery to fully run out of power before the unit can restart successfully then simply ensure that your device is recharged, then turn it back on. If you’re a Zune Pass subscriber, you may need to sync your device with your PC to refresh the rights to the subscription content you have downloaded to your device" Matt Akers, Zune product team, Microsoft
The section of code in question is only found on the Zune 30, hence only that model being affected. According to Microsoft's Matt Akers, of the Zune Product Team, a fix will be released at some point before 2012, when the leap year issue will next arise.
In the process of the fix, Zune Pass subscribers may temporarily lose their subscription content rights; this happens when the battery runs out and the PMP is restarted. Re-syncing the Zune with the authorized PC should restore these licenses. We'd be interested in hearing how Zune users get on with the "fix"; let us know in the comments.