Sorry to dig up this almost ancient topic, but I realized I'm having similar problems with some arduino pros ordered back in august.
These arduino pros are embedded into some interactive objects, and work without problems for weeks. then, all of a sudden, the device shuts down and becomes completely unresponsive. even reprogramming the bootloader with an isp programmer does not revive the chip. I've lost 3 boards so far.
I can't find problems in my wiring, so the only things im thinking of right now are:
- brownout when shutting down (can this demolish the chip?)
- overheating atmega (through overheating the regulator?)
- overcurrent on i/o pins, they are not protected by a resistor
so, i'm wondering whether any of you recognise these symptoms. I can replace the faulty devices, but the problem seems to be coming back. So, when does the device actually fail from overheating? (That is, in your experience, i know the datasheet specs)