Windows 8 Release Preview currently blocks the installation of Arduino drivers due to a missing signature in the driver file.
The steps below will help you to install them. It involves disabling some security, so not the best fix, but if you want your Arduino drivers working quick it’s the way to go.
*update: As per the wise suggestion of commenters, I’m noting that you must save any unsaved work before proceeding and read (and/or write down) all the instructions first. The reason for this is that the second line will reboot the computer into a startup options screen.
- Press the Windows Key and the ‘R’ key simultaneously
- Copy the command inside the brackets –>[ shutdown.exe /r /o /f /t 00 ]<-- ; paste it and "ok"
- Select ‘Troubleshoot’
- Select ‘Advanced options’
- Select ‘Startup Settings’
- Select ‘Disable Driver Signature Enforcement’
- Install driver as usual via device manager