Most hardware peripherals (printers, video input devices, scanners) use device drivers that have been 'digitally signed' by microsoft. Occasionally, you may need to install an unsigned device driver. The driver may be trustworthy, but becuase of a recent update may not be signed. Windows 7 will not allow unsigned drivers to be installed without special permission. These instructions show you how to allow unsigned device drivers to be installed.
- Go to: Start > Run
- Type gpedit.msc.
- Then browse to the following location:
Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options
- Find and double-click the following key:
Devices: Unsigned driver installaion behavior
- Change the behavior to:
- Restart the computer.
- Once the install was successful, use the same steps above to change the key back to the following for security reasons:
Warn but allow installation
Note: this option is not available in all versions of Windows
See the following Microsoft article for more information about driver signing: