Microsoft KB Archive/817900

= USB port may stop working after removing or inserting USB device =

Article ID: 817900

Article Last Modified on 5/19/2005

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APPLIES TO


 * Microsoft Windows XP Professional
 * Microsoft Windows XP Professional
 * Microsoft Windows XP Service Pack 1a
 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Service Pack 1a
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Web Edition
 * Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
 * Microsoft Windows Server 2003, Datacenter Edition for Itanium-Based Systems
 * Microsoft Windows Server 2003 Service Pack 1

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SUMMARY
When a USB device is repeatedly inserted and removed, the USB port may stop responding. This article describes how to resolve this problem with a unresponsive USB port.



Important This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry



SYMPTOMS
If you quickly and repeatedly insert and remove a USB device, the USB port may stop responding. When the port is in this state, it no longer recognizes any USB device.



CAUSE
This problem may occur because of a race condition in the Selective Suspend feature of USB. Microsoft and the hardware vendors that manufacture the chips that are used for USB have investigated the problem. However, the results have been inconclusive because of the intermittent nature of the problem.



RESOLUTION
To resolve this, follow these steps:
 * 1) Start Device Manager.
 * 2) On the Action menu, click Scan for New Hardware.

If this does not resolve the issue, you have to restart the computer. In some cases you must use Device Manager to disable then re-enable the device to get it to recover from this unresponsive condition.



WORKAROUND
Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To prevent this problem for server products where power management is not important or required, you can disable the selective suspend feature of USB. To do this, you must modify the following registry entry:

Entry: DisableSelectiveSuspend

Type: DWORD

Value: 1 disables selective suspend. 0 enables selective suspend

Note If this registry key is not present, you must create it.

This setting affects all USB host controller drivers in the system. If the DisableSelectiveSuspend value is set to 1, the selective suspend feature is turned off and the Allow the computer to turn off this device to save power check box does not appear on the Power Management tab for the USB Root Hub.



STATUS
Microsoft is researching this problem and will post more information in this article when the information becomes available.

Additional query words: plug unplug &quot;plug in&quot; &quot;plug out&quot;

Keywords: kbprb KB817900

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