Problem resolved. It did turn out to be the USB port. I pushed and pulled the plug in the port more forcefully than before. When I pulled out and u...

I have tried the following: - Uninstalled two MIDI drivers and restarted computer. Did not help. - Tried with a different computer, running Window...

Thank you Jason and Bad Mister for your quick responses. It looks like I have a list of things to try. I'll get back to you when I have done so.