Thanks Peter: I had it happen again several hours ago and I did load the Task Manager and, sure enough, there was a process tying up COM port 2. I right-clicked on the application and it identified the process as belonging to Chrome, which is the browser I use. Chrome has multiple processes running, but most of the time, none is identified as using COM port 2. I clicked on the End Process option, Chrome shut down, and the IDE was happy again. I can't identify what the process controls, nor do I remember doing anything but the usual within Chrome. Oh well, at least I know how to make it go away.
Thanks again...