When you plug a USB device into a Windows XP-based computer immediately after the computer resumes from standby or hibernation, the computer does not recognize the USB device. When this occurs, you receive the following warning message:
Unrecognized device has been found.
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CAUSE
When the computer resumes from standby or hibernation, there is a five-to-ten-se...
When the computer resumes from standby or hibernation, there is a five-to-ten-second period when the selective suspend feature of the USB driver interferes with detection of the new USB device. The time delay depends on the following factors:
* Host controller hardware
* Attached hubs
* Attached devices
* USB driver versions
* Support for USB 2.0
* Additional system hardware or configurations that may change the timing
For other causes that prevent a USB device from being detected, go to the "Similar Problems and Solutions" section to view related Microsoft Knowledge Base articles.
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Unplug the USB device, and then plug the device back into the computer or hub. If your computer still does not recognize the device, go to the "Workarounds" section.
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WORKAROUND
If your computer does not recognize the USB device, first try method 1 to work a...
If your computer does not recognize the USB device, first try method 1 to work around this issue.
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Method 1: Initiate recognition of the USB device by using Device Manager
To initiate recognition of the USB device by using Device Manager, follow these steps:
1. Click Start, click Run, type Devmgmt.msc, and then click OK. The Device Manager window opens.
2. Click to select your computer as the location for the scan.
3. On the Action menu, click Scan for hardware changes.
Windows XP recognizes the new device.
4. Close the Device Manager window.
If this method resolves the issue, you are finished.
If this method does not resolve the issue, go to method 2.
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Method 2: Disable power management of the USB hub
Note If you perform the following procedure, you may also reduce the battery life on a portable computer.
Use this method if method 1 does not work. To disable power management of the USB hub, follow these steps:
1. Click Start, click Run, type Devmgmt.msc, and then click OK. The Device Manager window opens.
2. Expand Universal Serial Bus controllers.
3. Right-click a USB Root Hub in the list, and then click Properties. The USB Root Hub Properties dialog box is displayed.
4. Click the Power Management tab.
5. Click to clear the Allow the computer to turn off this device to save power check box, and then click OK.
6. Repeat steps 3 through 6 for each USB Root Hub in the list.
7. On the Action menu, click Scan for hardware changes.
Windows XP recognizes the new device.
8. Close the Device Manager window.
If this method does not resolve the issue, go to method 3.
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Method 3: Restart the computer
To initiate recognition of the USB device, first unplug the USB device and restart the computer. Then, wait five to ten seconds before you plug the USB device into the computer or hub. Windows XP recognizes the new device.
If this method does not resolve the issue, you might want to review the articles in the "Similar Problems and Solutions" section, or contact Support. For information about how to contact Support, visit the following Microsoft Web site:
http://support.microsoft.com/contactus (
http://support.microsoft.com/contactus)
STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that ar...
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
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SIMILAR PROBLEMS AND SOLUTIONS
If the methods in this article do not resolve the issue, try the troubleshooting...
If the methods in this article do not resolve the issue, try the troubleshooting steps offered in similar Microsoft Knowledge Base articles. For more information about advanced troubleshooting tips for general USB problems, click the following article number to view the article in the Microsoft Knowledge Base:
310575 (
http://support.microsoft.com/kb/310575/ ) Advanced troubleshooting tips for general USB problems in Windows XP
For more information about how to troubleshoot unknown devices in Windows XP, click the following article number to view the article in the Microsoft Knowledge Base:
314464 (
http://support.microsoft.com/kb/314464/ ) How to troubleshoot unknown devices that are listed in Device Manager in Windows XP
If these articles do not resolve the issue, visit the following Microsoft Web site for information about how to contact Support:
http://support.microsoft.com/contactus (
http://support.microsoft.com/contactus)
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