When you connect a Pocket PC handheld device to a USB 2.0 hub, or when you turn off the device and then turn it back on again while the device is still connected to the USB 2.0 hub, Microsoft Windows may not redetect the device. This problem may also occur with other USB devices that have pending transfers if the device is disconnected and then reconnected; or if the device is turned off and then turned back on while it is still connected to the USB 2.0 hub.

Windows XP Fix

Windows 2000 Fix
SOURCE: Windows Knowledge Base