I have been able to remove virtually all traces of interference from dScaler. First I swapped out the an old WinTV card for an ATI TV wonder. This managed to reduce the noise but the interference was still evident. I have now replaced my Quiet PC PSU with a PowerPCcooling Silent 400 and the interference is gone. One word of warning though because even though this PSU is described as ultra quiet, it's not. To get around this problem I have replaced the PSU fan with a 12db Papst fan. I'm just glad that having spent $175 on a PSU and $20 on a replacement fan that it wasn't all for nothing!