My 810 was doing this and a couple of days ago every time I turned it on it would happen sooner and sooner. Now when I try and turn it on it begins booting and reboots again and again before it even has a chance to finish booting.

I want to cry, I will call nokia tomorrow about a warranty

Thought maybe it was related to the metalayer-crawler bug, but the symptoms don't quite match and none of the fixes helped. Sent it in to Nokia and they determined that it was not repairable. A new one is on the way, and all it cost me was one-way shipping. Couldn't ask for better. Thanks to everyone who gave suggestions.