Microsoft KB Archive/830758

= USB 1.1 devices do not work when you are running WinPE in Windows XP SP1 =

Article ID: 830758

Article Last Modified on 5/12/2004

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APPLIES TO


 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Professional

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SYMPTOMS
When you start your computer by using a Windows Preinstall Environment (WinPE) image that was built in a Microsoft Windows XP Service Pack 1 (SP1) environment, USB 1.1-compliant devices may not work.

Note USB 1.1-compliant devices include mouse devices and keyboards.



CAUSE
This issue occurs because the universal serial bus (USB) driver stack for Windows XP SP1 was modified so that a USB 2.0 host controller is always started before any one of its USB 1.1 companion controllers is started. This change was made to avoid enumeration conflicts that occur when a USB 1.1 companion controller is started before the USB 2.0 controller. Windows XP SP1 implements this change by using a 500-millisecond timer to poll the USB 2.0 controller to determine whether it is started before Windows starts the USB 1.1 controllers.

WinPE loads all required device drivers as boot devices. Sometimes, when Windows tries to enumerate attached USB devices, a USB 1.1 companion controller may not yet be started because of the 500-millisecond timer. In this scenario, any USB 1.1 device that is attached to that controller is not enumerated and therefore does not work.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
The Windows XP SP1 USB driver stack delays the start of USB 1.1-compatible controllers if they are paired with a USB 2.0 controller. This delay is designed to synchronize the start of the USB 2.0 controller with the start of the USB 1.1 controllers. This delay may prevent the USB driver stack from functioning as a boot device, and therefore all attached USB devices fail to function when WinPE successfully starts.

Keywords: kbbug KB830758

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