SYMPTOMS
When you plug a USB device into your Microsoft Windows XP-based computer immediately after the computer comes out of standby (S3) or hibernate (S4),
the computer may not recognize the USB device. When this issue occurs,
the USB device may or may not be listed in Device Manager as an unknown device,
and you may or may not receive the following warning message:
Unrecognized device has been found.
CAUSE
This issue occurs because, when the computer comes out of S3 or S4, there is a five- to ten-second period when the selective suspend
feature of the USB driver will interfere with detection of a new USB
device connection. The time period depends on several factors, including the following:
- 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
WORKAROUND
To work around this issue, use one of the following methods:
Method 1
After the computer comes out of S3 or S4, wait five to ten seconds before you plug the USB device into the computer or hub.
Method 2
After the computer comes out of S3 or S4, unplug the
USB device, and then plug the device back into the computer or hub.
Method 3
Use the Device Manager to scan for new hardware. Follow these
steps:
- Click Start, and then click
Run.
- Type Devmgmt.msc in the
Open box, and then click OK.
- On the Action menu, click Scan
for hardware changes. This causes Windows to recognize new devices.
- Close Device Manager and Control Panel.
Method 4
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.
To disable power management on
the USB hub, follow these steps:
- Click Start, and then click
Run.
- Type devmgmt.msc in the
Open box, and then click OK.
- Expand the Universal Serial Bus
controllers node, and then follow these steps for each USB Root Hub
that is listed:
- Right-click the USB Root Hub, and then click
Properties.
- Click the Power Management tab.
- Click to clear the Allow the computer to turn
off this device to save power check box, and then click
OK.