1995 BMW 325 cruise control erratic

Engine Performance problem
1995 BMW 325 6 cyl Two Wheel Drive Automatic

Hello,
This problem started about two months ago, when the cruise control would not respond three or four times on a 2000 mile trip. It would be working fine, then would suddenly not take hold. It would start working again after a stop, when the engine was again started. In the past several weeks it has happened increasingly frequently. It always works the first time after starting, but then stops responding after a time or two or three. Occasionally, but not often, it will start responding again without shutting the engine off. I do all my own maintenance, but have no experience with cruise controls, and have no idea how to determine the problem's source.