A USB 2.0 hub may stop working when you disconnect a USB 2.0 printer from your Windows XP-based computer

You disconnect a universal serial bus (USB) 2.0 printer from the USB port on your Windows XP-based computer. In this scenario, an external USB 2.0 hub that is connected directly to another USB port on your computer may stop working.

Note This problem may also affect a port replicator that works as a USB 2.0 hub.

This problem may occur if either of the following conditions is true:

• You are running Windows XP with Service Pack 1 (SP1), and you have installed the update that is described in the following article:
  
  822603  (http://support.microsoft.com/kb/822603/ ) Availability of the Windows XP Service Pack 1 USB 1.1 and 2.0 Update
• You are running Windows XP with Service Pack 2 (SP2) or a later version.

To work around this problem, use whichever of the following methods is best for your setup.

Method 1: Connect the USB 2.0 printer to the external USB 2.0 hub instead of to the USB port on your computer

If this workaround works for you, you are finished with this article. If this workaround is not a good solution for you, try Method 2.

Method 2: Disable power management of the USB 2.0 hub

Note This procedure may reduce the battery life on a portable computer.

1. Click Start, click Run, type devmgmt.msc, and then click OK.
2. On the View menu, click Devices by connection.
3. Expand the PC node.
   
   Note Because Microsoft Windows is installed on computers that use different types of processors, the PC node may be named differently on your computer. For example, the PC node might have any one of the following names:
   ACPI Multiprocessor PC
   ACPI Uniprocessor PC
   Advanced Configuration and Power Interface (ACPI) PC
   Standard PC
   
4. Expand the PCI-Bus node.
   
   Note If you do not see the PCI-Bus node, expand the current node, and then expand the PCI-Bus node.
5. Expand the Manufacturer and Model Enhanced Host Controller node.
6. Right-click the USB Root Hub node that is listed under the Manufacturer and Model Enhanced Host Controller node, and then click Properties.
7. Click the Power Management tab.
8. Click to clear the Allow the computer to turn off this device to save power check box, and then click OK.

If this workaround works for you, you are finished with this article. If this workaround is not a good solution for you, try Method 3.

Method 3: Edit the registry to disable selective suspend mode for all USB host controller drivers in the system

To have us fix this problem for you, go to the "Fix it for me" section. If you would rather fix this problem yourself, go to the "Let me fix it myself" section.

Fix this problem

To fix this problem automatically, click the Fix it for me link. Then, click Run in the File Download dialog box and follow the steps in this wizard.

Fix this problem
Microsoft Fix it 50052

Note this wizard may be in English only; however, the automatic fix also works for other language versions of Windows.

Note If you are not on the computer that has the problem, you can save the automatic fix to a flash drive or to a CD and then run it on the computer that has the problem.

Now go to the "Did this fix the problem?" section.

Let me fix it myself

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:

This procedure describes how to modify the following registry setting:Notes

• This procedure may reduce the battery life on a portable computer.
• This setting affects all USB host controller drivers in the system. If the value of the DisableSelectiveSuspend registry entry is set to 1, selective suspend mode is turned off. 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.

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
3. On the Edit menu, point to New, and then click Key.
4. Type USB for the name of the subkey, and then press ENTER.
5. Click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\USB
6. On the Edit menu, point to New, and then click DWORD Value.
7. Type DisableSelectiveSuspend for the name of the DWORD, and then press ENTER.
8. Right-click DisableSelectiveSuspend, and then click Modify.
9. In the Value data box, type 1, and then click OK.
10. Exit Registry Editor.

Now go to the "Did this fix the problem?" section.

Check whether the problem is fixed. If the problem is fixed, you are finished with this article. If the problem is not fixed, you can contact support (http://support.microsoft.com/contactus) .

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

In Windows XP, the USB core stack supports selective suspend mode. A driver can use this mode to turn off the USB device that the driver controls when the device becomes idle. This mode works even when the computer remains in a fully operational power state (S0). For example, a driver can make the following devices idle:

• The host controller.
• The USB hubs, including the root hub.
• The full range of USB devices that are supported by the operating system.

Selective suspend mode is primarily intended to conserve battery power in portable computers. Selective suspend mode helps reduce overall system power consumption by putting USB devices that are inactive in a low power state. This configuration increases battery life.