回複：usb的硬盤我家裏的電腦上（win XP)上沒反應

Is the u***** drive powered by dc adapter or u***** bus?
Can you see the device under USB controllers inside Device Manager? Is it shown as Unknown Device?
Try other u***** ports.
Check system log after you connect the drive. Right click My Computer, select Manage, select System under Event Viewer. Can you see an Error on the first line?