SYMPTOMS:
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.
CAUSE:
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:
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.
CAUSE:
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
Resolution :
If your computer does not recognize the USB device, first try
method 1 to work around this issue.
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.
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 your computer does not recognize the USB device, first try
method 1 to work around this issue.
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.
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.
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