Recently, my N810 has been caught in a reboot sequence. It will start to boot up, taking longer than usual. It will stay on the "hands" screen for a really long time, and then reboot. There is no way to stop it in this process, and the only way I have found to turn it off is to yank out the battery.

The only thing I can think of that may have cause this is Knips. I upgraded it and then tried to use it. It crashed, and I had to kill it. After that, all of my home-screen gadgets periodically crashed with a "database error". This would go away and work fine after a reboot.

Thank you for your help!

You need to reflash your system and you will lose anything on your tablets memory (not the internal or external card just where OS is installed) if you have a backup then you can install it and get your stuff back.

My n810 once got stuck in a reboot loop. This one time I got it past the hiccup by connecting it to mains power whilst it was in the middle of booting.
Weird, but it worked then. Worth a try.

You could also use the linux flasher to enable r&d mode and set the lifeguard-reset flag to off, then reboot, remove the offending application and use the flasher to set the lifeguard-reset flag to on again.