When I have the SR30C plugged in to the usb on the pc it says charging.
With the scanner on its scanning frequencies i put in manually.
OK so try this:
1) Disconnect the USB cable from your PC
2) Open Device Manager and expand the "Ports (COM and LPT) item
3) Write down all the devices shown
4) Plug the USB cable into the PC
5) Turn on your scanner
6) Plug USB cable into scanner
7) Go back and look at device manager again
If you don't see a new device, the first thing I would try is another USB cable.