Re the pixellation and sound dropping out. I have recently had problems with this and with my V+ box not recording the last few minutes of programmes despite the setting being put at +10 at end. I spent a frustrating 30 mins speaking to someone in India who asked me to do everything that I'd already done (Re-boot, check the settings, ventilation etc) and who then spent another 10 mins spaking to his supervisor - thank God its a free call! - but finally agreed to send an engineer.
When the engineer arrived he knew what the problem was straight away - the hard drive. He explained that the Samsung boxes have been made in Eastern Europe and Asia and there had been loads of problems with the ones made in Eastern Europe. He also explained that the reason it was happening whilst watching real time telly was because all of it has to go through the Hard Drive so that you can pause, rewind etc. (moment of realisation for me!!)
It was replaced a week ago and although the pixellation problem hasn't gone completely, I've only noticed it once since rather than virtually every programme.
So, if you are having these probs, might be worth a call?