Do you have any type of brake lights on the dash that are illuminated?? Do the tires actually lock up and skid?? When the pedal goes to the floor, do the brakes stay engaged or will the vehicle begin to move?? Have there been any recent repairs to the brake system??
Sorry about all of the questions. Most likely, if the pedal is going to the floor every time this happens, you have a brake master cylinderthat is bad and possibly an anti-lock brake problem. My concern is that no lights come on. The RED brake light is supposed to come if the pedal goes to the floor. The YELLOW anti-lock light is suppoed to come on if you most any kind of problem in that area. I would definitely recommend taking to a trusted and honest repair facility to get proper diagnostics on. Make sure you drive the vehicle and the service advisor with you for duplication of the problem. ANY braking problem can be dangerous. I recommend this as soon as possible.
If I can be of any other help,please let me know. Good Luck. Dave