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Device does not Appear after Clicking Safely Remove Hardware
http://www.vistaarticles.com/articles/247/1/Device-does-not-Appear-after-Clicking-Safely-Remove-Hardware
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Published on 12/10/2006
 
You cannot prepare Windows Vista for the removal of the USB device.

Device does not Appear after Clicking Safely Remove Hardware

To work around this problem, shut down the computer before you remove the USB device.

You may experience this problem if the following conditions are true:

The USB device contains an embedded USB hub.
The embedded USB hub detects a device that is connected to the USB hub as being a non-removable device.
This problem occurs because of the way in which Windows Vista handles devices that are connected to an embedded USB hub. If the Hub Descriptor component in an embedded USB hub reports downstream devices as non-removable, the Windows Vista hub driver propagates the non-removable characteristics of these devices to the operating system. The Safely Remove Hardware program in Windows Vista does not display devices which are non-removable. This behavior occurs because Windows Vista determines that you cannot remove a non-removable device.

In the scenario that is described in this article, Windows Vista determines that the embedded USB can be removed. However, Windows Vista determines that the downstream storage device or devices that are connected to the embedded USB hub cannot be removed.