I bought two Diecimila's from the ada fruit site. wrote my arduino code and my mac application with real basic and all was good. an associate bought 10 more Diecimila's from another site and now i am having random hanging issues of the arduino board when my app trys to connect to it. to troubleshoot this i have some code that blinks the led on and off in the loop. when i step through my mac applications code, when i get to the line that does serial1.open the led on the board stops blinking. if i reset the board with the reset button i can get it going again. this happens in between 1 and 5 trials on the new batch of boards. it never happens with my original two boards from ada fruit. i also have some code that blinks the led to let me now that i am in the setup routine. the proper behavior should be that everytime i launch my mac software when it does serial1.open the board should reset itself and run through the setup routine and then start looping. this is randomly failing on the new batch of boards. Could this be a chip problem? i noticed that the little 4 digit number above where it says ATMEGA168-20PU is different on the new batch of boards than on the 2 ada fruit boards. Or could it be some kind of bootloader problem?
Any help is greatly appreciated.