I've had my N900 since Jan. No probs til Friday.
Was browsing photos when it turned itself off.

Any attempts to turn back on and the phone would reset just after the nokia screen before it got to the hands shaking.

The only way to boot was to remove the SIM, which would indicate something wrong on the comms side. I tried to reflash the firmware using maemo flasher. Restored from backup and it will now boot with SIM but will not register onto the network. I can get on wifi fine.

I'm baffled. Any suggestions?