Try swapping the tv scarts around, ie: plug into scart 2 rather than 1? It sounds as though you are getting bleedthrough due to pin 8 being activated(this tells tv to swith to av when play of video is selected or dvd is switched on etc etc, except playstations which don't use pin 8). Its a common problem, sony and some other makes have output av settings in their menu or remote control. Sorry if i'm getting confusing? In a nutshell, by unplugging the scart in question from the tv whilst recording sky or cable will allow tv tuner to come through without any interference assuming the dvd is directly connected to the set top box rather than linking through the tv. Another solution is if you feel confident, to modify the scart lead by snipping the pin 8 cable inside the scart plug, but you need to be ok with selecting the appropriate AV channel manually on the TV remote. Maybe try it on a cheap or old scart lead to see? Hope this has helped.
mark g
May 2006