Recipe 3.2. Resolving Unknown Devices

Problem

You want to install new hardware but the Add New Hardware wizard fails to recognize the connection of a new device or fails to find an appropriate driver.

Solution

Using a graphical user interface

1. Disconnect the device from the PC to prevent recurring detection.

2. Uninstall the device driver:

   1. Right-click My Computer, select Properties.

   2. Select the Hardware tab then click Device Manager.

   3. Double-click Other Devices to expand, right-click the unknown device listed, and select Uninstall.

   4. Confirm the removal of the device, and then click OK to close the dialogs.

3. Install the proper device driver:

   1. Place the CD-ROM for the device in your CD or DVD drive.

   2. Run the setup program for the device software from the CD-ROM and follow the instructions, which usually include being prompted to reconnect the device and letting the Add New Hardware wizard find and associate the appropriate driver. (If you've lost the CD-ROM for your device, it's time for a visit to the hardware manufacturer's web site to download a current driver, install or unzip the files, and browse to the location of the files so Windows can install them.)

Discussion

Because many device manufacturers don't register their devices and drivers with Microsoft, Windows XP does not always have a reference point to find appropriate drivers. This symptom is frequently experienced when connecting a new USB device before installing the device driver for the device. Plug and Play may extract and present the proper make and model information from the attached device, but without a known driver, Windows banishes it as an "unknown device." Installing the device driver after the fact will not fix the problem because the device is already committed to the unknown category, so the "unknown device" must first be removed, and then you must install the proper driver before reconnecting the device. Unknown devices may be the modern-day "DLL hell" of Windows past.

See Also

Microsoft is quite familiar with the "unknown device" conundrum and offers several suggestions at MS KB 314464, "How to troubleshoot unknown devices that are listed in Device Manager in Windows XP," MS KB 161220, "Removing Unknown Device in Device Manager Hangs Computer," and MS KB 187723, "Plug and Play Printer Is Detected as an Unknown Device."