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USB devices may stop functioning correctly when multiple devices connected to the same USB hub go into selective suspend

Article ID: 968132 - View products that this article applies to.

SYMPTOMS

USB devices attached to the same hub are very slow or completely unresponsive.

While multiple devices that are attached to the same hub are going into selective suspend, one of the devices on the hub can receive a wake request. If this happens before the suspend request has completed, the devices become unstable.

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WORKAROUND

Try these methods to work around this problem.

Method 1 Disable and enable the USB root hub

Use Device Manager to disable and re-enable the USB root. This lets the controllers recover the USB port from its unresponsive condition.

To disable and re-enable the USB root, follow these steps:

Click Start, and then click Run.
In the Open box, type devmgmt.msc, and then click OK. Device Manager opens.
Expand Universal Serial Bus controllers.
Note You might have to scroll down the list to find this item.
Right-click the affected USB Root Hub, and then click Uninstall to remove it.
Restart the computer. After the computer starts, Windows will automatically scan for hardware changes and reinstall all the USB root hubs that you uninstalled.

After the computer restarts, check whether the problem is resolved. If this method resolved the problem, you are finished. If this method did not resolve the problem, go to Method 2.

Method 2 Restart the computer

Try restarting the computer. After the computer has restarted, check whether the problem is resolved.

If restarting the computer resolved the problem, you are finished. If this method did not resolve the problem, go to Method 3.

Method 3 Disable Selective Suspend feature

If the first two methods did not work for you, you can disable the Selective Suspend feature. However, be aware that when the Selective Suspend feature is disabled, all USB host controller drivers (and therefore all USB ports and connected USB devices) in the system are affected. Therefore, your computer cannot suspend any USB devices that are connected to it, and the USB devices can continue to use power while connected to the computer. 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.

You can disable the USB Selective Suspend feature by editing the registry. The USB device may become unresponsive because of a race condition in the Selective Suspend feature. The Selective Suspend feature suspends the USB device to efficiently maintain battery power by enabling the computer to turn off the USB device. However, sometimes this feature may not correctly wake up the USB device. Therefore, the USB device is unresponsive when you try to use it.

You might want to disable this feature for server products where power management is not important or required.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756

(http://support.microsoft.com/kb/322756/ )

How to back up and restore the registry in Windows

To disable the Selective Suspend feature, follow these steps:

Click Start, and then click Run.
Type regedit, and then click OK. Registry Editor opens.
Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\USB
If the DisableSelectiveSuspend registry entry is present, double-click it. If it is not present, create the entry. To create the entry, follow these steps:
1. On the Edit menu, point to New, and then click DWORD.
2. Type DisableSelectiveSuspend, and then press ENTER.
3. On the Edit menu, click Modify.
In the Value data field, type 1 to disable the Selective Suspend feature, and then click OK.
Exit Registry Editor.