I am assuming from your statement that your PC has never worked with your Beo5 ? Please confirm ?
Are you using version 1.02 of the Beo5 Configuration Tool ?
I think the best way to approach your problem is to un-install the driver if it has been installed.
To see the exact status of all your USB ports download HERE a small program which will give you a complete view of all your USB connections, working or not.
If it does not show a Beo5, then the driver is not loaded, which I think is most likely given everything else works. Look in "Device Manager" and see if any device has a yellow "!" next to it, if so that means it has detected the device, but cannot understand what the device is.
If this is the case, right click on the device with the yellow "!" and click "Update driver" which will force the driver wizard to run. Do NOT use the automatic driver loading, but click the manual and tell it where the driver. It is looking for a file called "Beo5Usb.inf" located in the following location:-
C:\Program Files\Bang & Olufsen\Beo5 Configuration Tool\Beo5Driver
You will need to manually browse to it and you will have to tell the Windows wizard the location twice.