If you’ve attached hardware devices to your computer and then later changed the hardware configuration, or retired the device, the driver you added to your OS may still be lurking. Ordinarily, this shouldn’t cause problems, but if a hidden driver accidentally becomes enabled, you may find that your computer takes a significant performance hit, starts to behave strangely or crashes during certain operations.

Making Hidden Drivers Visible

You may stray into the Device Manager, only to discover that the device driver doesn’t appear in the list of active drivers. That doesn’t mean the driver is gone, however. The Device Manager will “hide” drivers that belong to “non-present” devices. This could lead you to believe that the driver isn’t installed, when in fact, it’s installed and wreaking havoc on your system!

How do you get hidden drivers to show up in the Device Manager? You need to set an environment variable to force the Device Manager to show all of the drivers it knows about, instead of just the ones in use for devices that are physically attached to your computer.

Adding an environment variable sounds complicated, but it’s not. Go to the Start menu and right-click on Computer. Select Properties. On the left side of the panel that appears, choose the “Advanced System Settings” link. The computer will issue a User Account Control dialogue box that says “Windows needs your permission to continue.” Select Continue.

The Properties panel is divided into a number of tabs. On the “Advanced” tab at the bottom, you’ll find a button labeled “Environment Variables.” Select it.

The Environment Variables dialogue box will open. It’s divided into two panes; the first one controls user variables that apply only to the user that’s logged in. The second pane is a System variables pane that will apply to all user accounts. In this case, you’ll want to make the hidden device drivers visible to any user, so select the New button below the System variables box.

Enter devmgr_show_nonpresent_devices and enter a variable value of 1. Click OK on all open dialogue boxes. This change will force the Device Manager to show all hidden device drivers. Once these drivers are visible, you can use the Device Manager to remove old, unwanted, duplicate or orphaned drivers.

Device management programs like Driver Detective can also help you manage your drivers, whether they’re visible or hidden. Driver Detective will monitor and update your drivers, replace drivers that have been deleted or corrupted and remove drivers that are no longer needed.

Photo Credit: Ian Dick, via Flickr