Am I the only one

I have had my new Mazda since December 2009. 3 Dr 1.3 ts.
On many occasions now when applying the brakes, the car starts to brake then all of a sudden the brake pedal will grind/judder the brake will stop working so in turn I am skidding and then all of a sudden works again.
I am not good at explaining things but I hope you can understand what is happening here!
I took the car back to the dealer and they couldn't find anything wrong with it. They explained that if this was to happen it would register a fault that would be picked up the diagnostics machine but.....nothing was found. All he could tell me wasthat its just the abs kicking in and something to do with when the wheel leaves the road.
Two days later from the garage having it.....it happened again and continues to do so.
It really frightens me when it happens as I feel like I am going to crash. One time my son was in the car and it happened as I was slowing down at a roundabout and I just skidded out onto the roundabout. It was luckily not by much and luckily there was no cars on the roundabout but it certainly frightens me in my every day driving.
In all the years I have been driving and all the cars I have driven I have never experienced this.
Is there anyone one who has experienced the same and if so what has been done about it.
Many Thanks