The first time I saw it was after I had been exploring the hard drive. I got up to get something and came back after a couple minutes to find what I think is the Macbugs screen. If I pressed escape, I could get back to the desktop, but it was frozen. When I did a hard reboot, it started to go through the boot process, and then dropped into the same Macbugs screen. Pressing escape brought me back to the boot process, but it was frozen, requiring a hard reboot. After a few rounds of this, it just stopped spinning up the hard drive.
The error code from the programmers switch is when I press it right after powering up.
It was my understanding that in most electronics you can run a little over voltage and it wouldn't do harm, at least not to the device. I thought at worst it might put too much pressure on the power supply, making it run hot. I've only been running it for short amounts of time, but I'll hold off until I can get a more definitive answer or a real power supply.