I have the same setup and that problem happens to me sometimes. In my case, it seems to have something to do with the console as it is more likely to happen when I just had the console open and then press the upload sketch button without explicitly closing the console first. Sometimes, after I close the console and try to upload the sketch immediately after, I still get the message COMX already in use. Pressing the load sketch one more time then works for me.Rui
The question is, however, why did this suddenly start happening after several weeks of perfect operation, during which I've been streaming data off the board? We have several more boards on order. Will this be a recurrent problem, or does it only happen with some hardware?