Sometimes the device manager just won’t open for whatever reason.  This happened to me before and I don’t know why.  Either way, this is how to do it without going to the control panel.  This how-to involves the use of the Microsoft Management Console.  I have no idea what it does, I just know that it will let me into the device manager.

  1. Start > Run (or winkey + r)
  2. Type “mmc” and click OK
  3. Click File > Add/Remove Snap-in…
  4. Select Device Manager from the left menu and click the Add button.
  5. Click OK

The device manager should now be visible in the left pane of the mmc window.

Source: http://www.theeldergeek.com/forum/index.php?showtopic=10065