Drivers can come from many different sources, like an installation CD, a web site, or other various sources. Some device drivers are not digitally signed by Microsoft, which could mean that they may not have been tested as thoroughly as they could have been. There's a greater chance that they could effect the stability of your system because of unknown compatibility issues.
To configure how these signed and unsigned drivers are handled by the OS, you need to open the 'Driver Signing Options' dialog:
- Open the Control Panel folder.
- Double click the System applet.
- Click the Hardware tab.
- Press the 'Driver Signing' button.
- Ignore (Allows the installation of any files, signed or not.)
- Warn (Displays a warning message that the driver being installed is not signed.) [Default]
- Block (Prevents the installation of unsigned drivers).