Got to comment that USB doesn't seem to be quite as reliable and fool proof as I would like ... and have learnt (the hard way!) that the best course of action is to simply to get into device manager and simply delete any USB device with a yellow exclamation mark -- and then re-install the device. And as a general rule (particularly with devices that install more than one type of device in hardware manager - typically printers install USB ports as well as USB devices), you need to install the software before plugging in the device. Plug & Play ain't always what its name implies!