Samsung LE32R74 dtv picture awful

[encephalopathy]

as above - when i use the built in freeview there are all sorts of blue blocky artefacts especially on light coloured areas of the picture

not present on the sd signal

if i use my phillips freeview box the problem is the same, whereas before with my crt tv its picture using the philips freeview box was fine

dvds play ok without any artefacts

any ideas what is causing this or is it just due to the quality of my freeview signal?

thanks

 

[encephalopathy]

oh i feel like such a plonker

pushed the scart lead in a little more snuggly and artefacts are gone

think i will get some better scart leads - are the ones that 'lock' in place better, or more likely to rip part of my tv off?