PC doesn't recognize USB device.
Possible to check with the device manager.
1) Open [control panel] in [settings] - [start].
2) Open [system properties] with double click on the [system] icon.
3) Click [device manager] tab, and choose [view devices by type].
4) Click [+] mark beside [universal serial bus contoroller], 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.