The clutch switch or brake switch move up on my list of potential culprits if the intermittant cruise drops out after running over an expansion joint in the road.
I also believe (It's been a while since I looked) that the brake pedal arm has two switches. One, contacts normally closed and held open when the pedal is up, operates the brake lamps. The other, normally open and held closed when the pedal is up, maintains the cruise.
In other words, brake light operation has nothing to do with cruise operation. These are two different switches, one opens to cut power, the other closes to supply power.