N900 had USB Networking and several programs running; battery fully charged, green LED. And then, when I tried to use it, the black screen cannot unlock. Thanks to USB networking, I ssh'ed into it.

espeak works, I can hear it.
killall hildon-desktop
and
killall hildon-home
already tried.
kilall hildon-input-method
and
killall fennec
also, just in case.

Modrana isn't running.
Cellular connection and GPS and WiFi are off. WiFi module is most likely unloaded by WiFi switcher.

So, what is your advice? It's an ideal testcase, I think. The problem would be resolved by taking the battery out, but I don't want to. There are no unsaved documents. The only applications running now are: Filebox, X Terminal, Leafpad. What do you think?

EDIT: Ok, it's boring, I have just taken out the battery and restarted it.

Sounds like maybe it is the same problem as in bug 9150:

http://bugs.maemo.org/show_bug.cgi?id=9150

Yes, [sgx_misr] was taking 99% of CPU. It's definitely this bug. And this bug definitely requires neither GPS nor Wi-Fi nor cellular connection nor Modrana.

Yes, there can be multiple reasons/triggers. Highlights the importance of getting exact, reproducible steps and exact environment setup for reproducing the issue.