At about 10:15 pm edt, july 31, 2015, i was driving my 2001 chrysler prowler east on interstate 64 in virginia. i was between exit 167 and exit 171. i was traveling at 60 mph and noticed that the green "cruise control on" light on my dashboard was on. i had not turned the cruise control on. i attempted to turn the cruise control off. the cruise control would not turn off...it also would not allow me to reduce my speed. using my brakes, i slowed the car, left the highway at exit 171, pulled into a gas station parking lot, and turned the car off with the ignition key while the car was in gear. after turning the car off i put the transmission into park position. when i had calmed down i turned the car back on. the cruise control was no longer on and drove to my destination. i found this situation to be both frightening and annoying.