Why doesn't the PC recognize USB device?
Check with the device manager to see if the USB controller works properly.
1) Open [Control Panel] in [Settings] -> [Start].
2) Double click on the [System] icon to open [System Properties].
3) Click [Device manager] tab and choose [View Devices by Type].
4) Click [+] mark beside [Universal Serial Bus Controller] and see the [------- host controller] and [USB root hub].
5) [USB controller] works properly if there is no [!] or [X] mark on it.
* Re-install the driver which has [!] or [X] mark.
* Re-install USB device driver, when USB controller works properly but doesn't recognize USB device.