Using a MacPro with OS X Yosemite and a 30: Cinema Display. The Cinema HD Preferences-Options-Brightness Buttons check box keeps defaulting to Dusable brightness buttons. Even after I unlock Preferences to uncheck it, it reactivates automatically.

Thank you for replying Bennet-Alder. I just unplugged and replugged in the back of the MacPro the USB cable from the adapter to see if that would help and now the Options section of the Display System Preferences completely disappeared.

Thank you for replying Bennet-Alder. I just unplugged and replugged the USB cable from the adapter in the back of the MacPro to see if that would help and now the Options section of the Display System Preferences completely disappeared. Next I did the same, but swapped with another USB that was plugged in and all is working. It seems the USB ports are finicky. I'm using all of the ports, and one is to a USB hub, is it possible that having too many USB devices plugged in can cause this problem?