Every time you connect a new device to Windows, its information get added to the Registry. One of the ideas behind this is to improve device discovery on consecutive connects to the PC. Some users, especially those who connect a wide variety of devices to their system, or have done so in the past, experience slower start up times because of this. How? To find out whether a device is present but not connected, is to try to connect to it. And since this is done during startup, it may increase the time it takes to boot into the Windows operating system.
We have explained before how you can remove old Windows device drivers manually from the system, but it requires you to change a configuration setting first, and uninstall each device manually from the Windows Device Manager.
Ghostbuster is a free program for Windows, requiring the Microsoft .NET Framework 3.5, that automates part of the process. When you first start the program, you will see a list of all removable devices, sorted into groups like human interface devices, disk drives or portable devices.
It lists all known devices belonging into the group, and the device's status. If you see ghosted there, it means that the device is currently not connected, but known by Windows. You can now remove ghosted devices by selecting them and clicking on the remove ghosts button afterwards.
The core benefit of using Ghostbuster is that you see all hidden devices right away, and that you can remove them with two clicks.
Sometimes you may need to do additional research before you remove devices. This is especially the case if you can't identify a device right away, for instance if its name is too generic, or if it is listed multiple times, and you are not sure if you can remove one of the instances or not.
The description the program displays may help in some cases. It may consist of a drive letter or name for instance, which may give you an idea whether you should keep it or not.
Windows usually will install the hardware anew if you have removed something that is still needed by the operating system. Keep in mind though that this may not be the case for core devices listed here, and that you may end up with a non-functional operating system if you remove the wrong devices.
If there is something to criticize, it is the lack of research options built into the program, and a missing backup and restoration option.
Still, it is a solid program to remove device information from devices that you no longer connect to the PC, for instance if you do not own the device anymore, or have moved to another. (via Raymond)