i am definitely using the programming port. i have determined that i need to press reset to make sure that either the loaded program is running or that memory is erased. then i need to press reset again before loading the program. if i upload a program and the comport not found error occurs, the memory has in fact been erased because the program is no longer there. so there really is communication via the serial port to erase the memory. it seems that two attempts are needed each time, one to erase memory and one to program. if i press the erase button manually, i can then press reset once and succeed at uploading every time.
i have two different boards and both behave the same. they have different stuff connected and different programs. on one, the erase button is accessible so it was no big deal.
i don't mind pressing reset several times and attempting to upload a couple of times. what kills me is having to wait to compile and verify the program only to find it will not upload. IS THERE SOME WAY TO JUST UPLOAD THE LAST COMPILED PROGRAM AND NOT HAVE TO RECOMPILE?
also, what do you mean by have a look at the USB port? what should i be looking for? also what should i be looking for in terms of hardware on the board? i have two boards that behave the same so i doubt it is a mfg error unless it is a problem with a run of boards that all have the same problem. i bought both of them from Digikey in fairly close succession so maybe they are of the same batch.