I'm pretty sure this is a driver issue, which means anyone could see it. I think it just happens more often when one or more of the following is going on:

• Program is doing CPU intensive work
• System free memory is low
• Graphic redraw is high (high frame rate apps)
• GPS is active
• Heavy Wifi/3G/GPRS data activity, and/or mode switching.

If you have an app doing several of these things at once, like a flash game (CPU/graphics/wifi), or a navigation app (GPS/CPU/memory), it's just more likely to happen.

My phone woke me a 5am today, warning of a reboot... Totally inactive, but sure enough sgx_misr was pegging the CPU & screen wouldn't turn on. It rebooted itself and everything was fine. Had I not had the script, it would have drained the battery (even while plugged in), and I'd have had a dead/off phone this morning when I awoke.