Indeed - not knowing which firmware version was installed doesn't help, and I don't know anyone else with an n800 who's in a position to be able to reflash it to an old firmware version in order to help. I ended up reflashing my n800 today after convincing myself that everything important was likely on the SD cards. Thanks for your help everyone! Now to reinstall all the programs, rewrite some scripts, reenter my wifi and web passwords, etc, etc.