Microsoft's Tripp Parks tweeted me this morning about a shiny new update (2727113) now available on Windows Update for Windows 8 users. The new update finally resolves the freezing issue on Windows 8, woo hoo! The KB article describes the symptoms and cause as such:
On a computer that is running Windows 8 Release Preview or Windows Server 2012 Release Candidate, the system may randomly stop responding (hang) when you work on multimedia or communication activities. This problem may occur during video editing, unified communications, or other multimedia activities.
This problem may occur because of an issue in the interaction between the state-machine driving dynamic tick transitions and the state-machine-driving clock rate changes.
Reminder: If you previously applied the bcdedit workaround, issue the following command to undo that, then reboot:
bcdedit /set disabledynamictick no