If you are using a wireless usb mouse, unplug it for a moment and see if the computer recognizes the walkman. I was having the same issue then unplugged my recently added usb mouse while the walkman was still plugged in. Boom - the computer instantly saw the walkman and started charging etc. I had to plug the wireless usb mouse into the back of my pc and everything was happy again! Must be some sort of interference by using 2 ports next to one another.