Last weekend, took the gang for a drive in the mountains. Nothing major... typical wash-board and some rocks. When we were back on the highway, I tried to set the cruise control and it would not take. Tried several more times... still no dice. Seems to have 'self-repaired' once ignition was turned off, and then re-started truck. Hasn't happened again since. Obviously, terrain-related, but does anyone have any ideas???