peugeot 206 Automatic 'W.Reg'?

I bought recently a peugeot 206 Automatic gearbox, while driving it and break and the car comes to a stand still I hear a noticible CLICK from the gearbox, I noticed that nearly every time I stop while the Transmition on Drive that makes the car trumble for a second..... can anyone advise me on what to check for and what might be the provisionale problem, Car has only 44000 on the clock... PLEASE HELP