Welcome! Please drop by the Newbie board and introduce yourself to the others on here. Nice gang we've got.
I've had other weirdness with my cruise control, but not quite like you describe. Mine will go for days refusing to engage, then it starts working again. Its been behaving well for maybe 6 months now, but last summer/fall it seemed to be a week on and a week off. Hard to figure. My only suggestion is maybe its linked to the clutch switch? Mine is a manual and the clutch sometimes prevents starting, a problem I solve by turning off the ignition, depressing the clutch again, and voila, it starts. I haven't had the starting problem since I had the cruise problem which is my only reason for suggesting the link.
Neither problem was ever solved, they just went away. My fingers are crossed.