Bought a KDL-V402500 about two months ago. Since then, I have noticed a series of clicking sounds that come from the rear of the unit which seem to lessen in recurrence after the tv is on for an extended period.
My Samsung makes clicking sounds from back. I had a tech come out and said the tv was fine. I think it's from condensing from hot/cold weather. It seems to have lessen.
I don't know if this applies to LCDs, but with plasmas as the barometric pressure decreases there is less pressure against the two outer glass plates which can result in audible vibration.