JSI Tip 9708. A device may not establish a connection with a desktop computer when you try to connect it through an external USB port hub, in Windows XP, or in Windows Server 2003?

When you attempt to connect a device through an external USB port hub, Windows XP or Windows Server 2003 may not establish a connection to your desktop computer.

This behavior occurs because of a race condition in the Selective Suspend feature of the USB hub driver.

NOTE: The Selective Suspend feature suspends the USB hub to maintain battery power on a laptop.

To workaround this problem, you can use any of the following:

. Use Device Manager (devmgmt.msc) to Scan for hardware changes on the Action menu.

. Shutdown and restart your computer.

To resolve the problem on your desktop computer, disable the Selective Suspend feature of the USB hub driver:

1. Open a CMD.EXE window.

2. Type the following command and press Enter:

REG ADD HKLM\SYSTEM\CurrentControlSet\Services\USB /V DisableSelectiveSuspend /T REG_DWORD /F /D 1

3. You will need to restart your computer for this setting to become effective.

NOTE: Setting DisableSelectiveSuspend to 1 may decrease the battery life on a laptop.

NOTE: Setting DisableSelectiveSuspend to 1 affects all USB host controller drivers on your computer. It removes the Allow the computer to turn off this device to save power box from the Power Management tab of the USB root hub.



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