Was wondering if anyone could help. I was quite hapily driving along today going into town, approaching the roundabout when I heard a knock and felt something hit the floor of the car, so I looked in my rear view to see something bouncing along the road (I thought it was some random object), I then push my brakes and theres nothing

....felt just like the clutch. Then after a few pumps of the pedal they came back on again. I pulled over to see if there was anything wrong with the brakes, and I find that one of my drivers side rear pads had fell out!

Has anyone had this problem before? If so, what causes it?
Luke