My Toshiba has sound issues?

I bought a 37" Regza last December and came upon the "dalek" sound. Thought it was an issue with my DVD (Replaced 2 times and sound card replaced). Then after advice changed what HDMI connections on the back of the TV I was using. Still the same problem!!! Having put up with it, we then bought a 40" Regza and within 2 days, we get the "dalek" sound again. Will be progressing this with John Lewis in the morning and sending them the web page. Will be looking for action based on what I have learned from here too........