You may have a point there. It very well could be heat related.
The first power up today I timed and malfunctions started at 58 seconds after power up. After power cycling with no cool down time it goes straight into freakout mode. If the QCX sits for a bit before applying power again it takes between 0 and 30s to start malfunctioning.
I'll look and see if I can find some canned air. Very good idea.
Unfortunately I don't have another ATMega328 laying around to try.