Car starts rolling again after brakes pressed?

My girlfriends Ford Taurus stops like normal when the brake is pressed, but then after stopping completely it makes a rough sounding noise and starts rolling like the brake isn't pressed down, but it is. Any help would be appreciated.

Need new brake pads it's that the pad it doesn't have any left to lock on the disc so it starts to slowly move again what happens is that is like tires when new thread it has enough to stop good but when there's no thread left it slides…

The car is getting ready to kill you and your girlfriend, (and others), and you're asking the Internet? Have the thing towed to a mechanic. You've got a leak somewhere; master cylinder, disk / drum cylinder, or brake lines.