Microsoft KB Archive/324756

= You Cannot Simultaneously Use Multiple USB Scanners in Windows XP =

Article ID: 324756

Article Last Modified on 7/14/2002

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APPLIES TO


 * Microsoft Windows XP Professional Edition
 * Microsoft Windows XP Home Edition

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This article was previously published under Q324756



SYMPTOMS
You may not be able to install multiple Universal Serial Bus (USB) scanners in Windows XP and use them simultaneously. For example, when you attach two scanners to the Universal Serial Bus (USB) ports of your Windows XP-based computer, the first scanner that you connect is detected correctly; however, when you connect the second scanner, you may experience one of the following behaviors:  The second scanner is listed in Device Manager as &quot;Unknown Device&quot;.

-or- You receive the following error message (it is displayed next to the scanner in Device Manager):

Windows cannot load the device driver for this hardware because a previous instance of the device driver is still in memory. (Code 38)





CAUSE
This behavior occurs because the Usbscan.sys driver cannot be used simultaneously by more than one scanner.



RESOLUTION
To work around this issue, connect and use one scanner at a time. To use the second scanner, disconnect the first scanner from the USB port, restart the computer, and then connect the second scanner. To use the first scanner, disconnect the second scanner from the USB port, restart the computer, and then connect the first scanner.



MORE INFORMATION
For additional information about how to manage devices by using Device Manager, click the article number below to view the article in the Microsoft Knowledge Base:

283658 How to Manage Devices in Windows XP

For additional information about how to troubleshoot device conflicts by using Device Manager, click the article numbers below to view the articles in the Microsoft Knowledge Base:

310126 Troubleshooting Device Conflicts with Device Manager

310123 Explanation of Error Codes Generated by Device Manager

The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

Keywords: kbprb KB324756

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