Method 1 resolved the problem before, but it's come up again. When I've run
through Method 1 again, the light on my USB device comes on and it seems to
be doing something. However, it doesn't appear at all with a drive letter in
"My Computer".
Also, in the device manager, one of the items called "USB Mass Storage
Device" has a yellow exclamation point to it. The error says "Windows is
uninstalling this device. (Code 21)". However, that error has been there a
long time and nothing seems to be uninstalling at all.
"donald huang" wrote:
> Here are some methods helping the computer to recognize the USB devices
> plugged in.
>
> 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:
> Click Start, click Run, type Devmgmt.msc, and then click OK. The Device
> Manager window opens.
> Click to select your computer as the location for the scan.
> On the Action menu, click Scan for hardware changes.
>
> Windows recognizes the new device.
> 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.
> Back to the top
> 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:
> Click Start, click Run, type Devmgmt.msc, and then click OK. The Device
> Manager window opens.
> Expand Universal Serial Bus controllers.
> Right-click a USB Root Hub in the list, and then click Properties. The USB
> Root Hub Properties dialog box is displayed.
> 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.
> Repeat steps 3 through 6 for each USB Root Hub in the list.
> On the Action menu, click Scan for hardware changes.
>
> Windows recognizes the new device.
> Close the Device Manager window.
> If this method does not resolve the issue, go to method 3.
> Back to the top
> Method 3: Restart the computer
>
> Other things to try: identify the version of the USB device and the port on
> your computer and make sure they are the same. It is said that USB 2.0 and
> USB 1.1 or 1.0 ports and devices cooperate with each other but sometimes it
> depends on the features of your devices. Make sure the current drivers are
> installed and the devices are with plenty power supply if there are any. It
> is better not to use over 3 USB devices on a single computer at the same
> time.
>
> To know if my PC has USB 2.0:
> You can identify whether your PC has Hi-Speed USB or not relatively easy.
> Open Device Manager and expand the Universal Serial Bus section. There
> should be an "Enhanced" USB host controller present.
>
> "Ken W" <> wrote in message
> news:34372CA0-4ACA-4997-A242-...
> > When I plug in certain USB devices, sometimes my PC doesn't recognize
> > them.
> > There are certain USB devices it always recognizes. There are others that
> > it
> > never recognizes. Then there's one that it was recognizing, but it no
> > longer
> > is.
>
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