In a recent edition of the Microsoft Windows Vista and Windows 7 Report, "Troubleshoot Vista System Drivers More Efficiently with These Tools," I told you that while many of the most common driver problems have been solved, you may still incur strange or erratic problems related to drivers in Vista. I then showed you a couple of tools (Driver Query and Driver View) that you can use to gather information on device drivers. However, I was reminded that Windows Vista retains old drivers even if you upgrade or change hardware.
For example, Vista knows that removable USB devices aren't always connected, but it retains the drivers so that they will be ready the next time you connect the device. So what happens to that driver if you never connect that device to your computer again?
Over time these unused, but still installed, drivers can cause problems if they inadvertently become enabled. They can cause hardware conflicts or just cause the system to behave erratically. Fortunately, in addition to using the tools described in the previous article, when you're troubleshooting a problem in Vista that you suspect is related to a driver, you can locate and remove any old and unused drivers by enabling a special feature in Device Manager that allows it to display non-present devices.
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Activating non-present devices modeIn order to configure Device Manager to display non-present devices you will need to add an environment variable DEVMGR_SHOW_NONPRESENT_DEVICES to the Environment Variables dialog box. To begin, access the Start menu, right-click on Computer, and select the Properties command. When you see the System window, select the Advanced System Settings link, as shown in Figure A. When you do, you'll encounter a UAC and will have to deal with it appropriately.
Once the System window appears, select the Advanced System Settings link.When the System Properties dialog box appears, click the Environment Variables button, as shown in Figure B.
Locate and click the Environment Variables button at the bottom of the System Properties dialog box.When you see the Environment Variables dialog box, shown in Figure C, you'll see that it contains two panels titled User Variables and System Variables. Environment variables added to the User Variables panel will be available only when that user logs on. Environment variables added to the System Variables panel will be available to all users. To avoid limiting yourself to one user account, I recommend that you add the devmgr_show_nonpresent_devices environment variable to the System Variables panel.
You'll click the New button in the System Variables panel.Click the New button. When the New System Variable dialog box appears, type devmgr_show_nonpresent_devices in the Variable Name text box and type 1 in the Variable Value text box, as shown in Figure D.
Use the New System Variable dialog box to set up the new environment variable.
Then, click OK twice -- once to close the New System Variable dialog box and once to close the Environment Variables dialog box.
Removing non-present devices in Device ManagerTo view the non-present devices, access the Start menu, right-click on Computer, and select Manage. When the Computer Management window appears, select Device Manager. Once Device Manager is active, pull down the View menu and select Show Hidden Devices. Now, open the various branches in the Device Manager tree and look for device icons that appear translucent or faded. On my example system I found a slew of non-present devices, as shown in Figure E.
Non-present devices have icons that appear translucent or faded.
To remove the device drivers for any of the non-present devices, simply right-click on the faded icon and select the Uninstall command. Once you are done, close Device Manager and just for good measure, restart your system.
What's your take on driver problems?
Have you encountered problems with drivers in Windows Vista? Will you use Device Manager's non-present devices mode? As always, if you have comments or information to share about this topic, please take a moment to drop by the Discussion area and let us hear from you.
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Greg Shultz is a freelance Technical Writer. Previously, he has worked as Documentation Specialist in the software industry, a Technical Support Specialist in educational industry, and a Technical Journalist in the computer publishing industry.