The [lock up] happened to my Nokia Lumia 920 this morning when trying to launch the ESPN ScoreCenter app from my start screen. I’m not sure what might have caused the lockup, but whatever it was made the screen freeze in that state. I tried holding down the power button for 10 seconds but that did not work.
After doing some research online I discovered a way to reboot the phone when it freezes up. This applies to all Windows Phone devices, not just the newer ones.
Simply hold the lock button and volume down button at the same time for 5-10 seconds. Once the phone reboots you can now get back into the operating system and make sure everything is normal.
This should not affect your settings, messages, photos, contacts, etc. This function simply reboots your phone without forcing you to do a backup, although it’s highly recommended to back up your phone often.
Good to know. So that's two possible key operations to try when your Windows Phone device freezes harder than ice cream in Antarctica.
Mind you, I still hanker for being able to pull the battery though.... mutter, mutter....