I have had my Pioneer 434 up and running for neraly 2 weeks now and am really enjoying it. The PQ is excellent and as has been said by many here, the quality improves daily. But, and there's always a but, I have noticed a slight change in the picture brightness occurring from time to time. It is more noticeable on light scenes but the picture can be seen to get slightly darker and then almost as quickly go back to the same level again. This happens on RF, DVD and SKY+. Both the DVD and SKY+ are connected via RGB into Input 3 on the Media box. The change is very quick and can happen at any time, albeit not that often. Is this a fault or merely a 'characteristic' of the screen (either Pioneer or Plasma in general)? I have adjusted the contrast and brightness down during the running in period but adjusting this during tinkering sessions doesn't have any impact on it. As I say this is very sporadic and my wife hasn't noticed it, but I would love to find out why this is happening. Can anyone help?