Point taken, James C4S ;). Blink does not work either. The two Megas are identical. Purchased at the same time from Newark. In the meantime, I was able to fix my sketch via the Mac, and then run it on the troubled Mega. The sketch involves talking to LabVIEW on my Win7 machine via USB. This works perfectly, no issues at all...It seems everybody is happy with this Mega, except the Windows Arduino 1.0 IDE. I probably should have never 'upgraded'...only headache since leaving 0022 behind!!