Remove device drivers that are no longer used in Win7?

                  How to remove the old device drivers that are no longer used in Win7? If you find that some recently installed devices are not working properly or are causing computer crashes, then you can consider removing old or unused device drivers from Windows 7.
Just do it:
1. Right-click on the "Computer" of the Win7 desktop and select "Properties".
2, find "Advanced System Settings" on the left panel, click "Environment Variables" at the bottom of the "Advanced" tab.
3, in the upper part of the "XX user variables" click "new"
input variable name: devmgr_show_nonpresent_devices
input variable value: 1
OK, OK, and then determine!

4. Right-click on the "Computer" on the desktop, select "Manage", and open "Device Manager" on the left.
5, in the top menu bar of the device manager, select "View" - "Show hidden devices."
6, so You can find "other devices" on the right side of the device manager.
7, right-click "unknown device", uninstall it!

That's all