Hope I can explain this.
I have an old Umax scanner that connects through USB.
I only use it once or twice a month, so I leave it unplugged.
Now, when I try to use it and plug it in I get a widow from the service tray that says there is an unknown device plugged in. In the Device Manager there isn't any Imaging Device listed. So I have to reload the Diver CD and reinstall every time. Sometimes I have to do it two or three times before it takes.
The next time I turn it on, the drivers' gone. This has even happened when I have left the scanner on and connected.
My printer and other USB device seem unaffected.
I have know idea what is going on, but it is frustrating .