Microsoft KB Archive/902274

= A device may not establish a connection with a desktop computer when you try to connect the device to the desktop computer through an external USB port hub in Windows XP or in Windows Server 2003 =

Article ID: 902274

Article Last Modified on 8/8/2005

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APPLIES TO


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

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Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry



SYMPTOMS
When you try to connect a device to a desktop computer that is running Microsoft Windows XP or Microsoft Windows Server 2003, the device may not establish a connection with the desktop computer. This problem occurs when you try to connect the device to the desktop computer through an external USB port hub.



CAUSE
This problem occurs because of a race condition in the Selective Suspend feature of the USB hub driver. The Selective Suspend feature is designed to suspend the USB hub to efficiently maintain battery power. However, the Selective Suspend feature sometimes may not correctly wake up the USB hub.



RESOLUTION
To resolve this problem, use one or more of the following methods.

Method 1
In Device Manager, scan for hardware changes. To do this, follow these steps:
 * 1) Start Device Manager.
 * 2) On the Action menu, click Scan for hardware changes.

Method 2
Shut down and then restart the computer.

Method 3
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

Disable the Selective Suspend feature of the USB hub driver. To do this, follow these steps:  Click Start, click Run, type regedit, and then click OK. Locate and then click the following key in the registry:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\USB

 On the Edit menu, point to New, and then click DWORD. Type DisableSelectiveSuspend, and then press ENTER. On the Edit menu, click Modify. Type 1, and then click OK.</li></ol>

Note If the DisableSelectiveSuspend registry subkey is not present, you must create this registry subkey. This setting affects all USB host controller drivers in the system.

If the DisableSelectiveSuspend value is set to 1, the Selective Suspend feature is disabled. Additionally, 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.

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MORE INFORMATION
For more information, click the following article number to view the article in the Microsoft Knowledge Base:

817900 USB port may stop working after removing or inserting USB device

Keywords: kbtshoot kbprb KB902274

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