Yes I understand it's the video device. Apologies for not ordering my thoughts better in my last post. With luck there will be an open SGX driver someday. And a non-2.6.28 kernel! And... sigh.

Incidentally my device was in offline mode during these tests, to conserve battery life and avoid roaming charges. So my crashes couldn't have involved either GSM or GPS use.

If the problem continues, I will likely try your reboot script/driver. It appears to be a useful workaround, but I hate that such a workaround is necessary on N900 when other Linux systems are so robust!