Dark picture on composite inputs ?

Question

Hi,When I'm using the composite inputs (both of them) I get dark picture, really ugly :(. At the moment I switch to analog input the picture is good, but I dont have the HDTV quality anymore.The technician from Time Warner come and we tried brand new set-top/decoder box. He unpacked it in front of me.That is why I think it has something to do with my Olevia ?Is this easy fixable... send an email to Olevia nobody bothered to answer. What could be the problem.thanx in advance