home theatre sound lag, could it be my optical lead?

i have a samsung thx35 theatre system, when watching a dvd the sound is spot on, but when i use the theatre system to listen to sound from the tv or xbox360, it is delayed, i am using a samsung 42" tv, i have tried to correct it by using the sound delay feature in the theatre system but this makes it worse, i am using an optical lead for the sound, could this be my problem and how do i get my sound perfect, it is really annoying? samsung say they cannot help me!

signal delay has become more prevalent because every piece of gear now has a signal processor built into it. unfortunately for you, you’ve got a white elephant, an orphaned piece of gear no longer supported by the manufacturer. it’s easy to delay sound, video delay lines are pricey and harder to find. you’ll have to route the signal so you can switch the delay in for the offending sources and out for the dvd. good luck