Toshiba Regza 42" TV sound goes off randomly?

I bought my Toshiba Regza TV in november 2008 and now (september 2010) we are expereincing sound issues. About three weeks ago whilst watching TV the sound would occassionally (about 4 times in 3 hours) go very very low. Over the past week, rather than the sound going low it just cuts out. The picture is fine.

The frequency of its occurance varies in a night, however it is pretty much daily. For example whilst watching an hour long program it did it 4 times and once would not come back on for another 30 mins, however last night it happenned only once in three hours.

It appears it happens more on programmes that are being played back via sky+ then live ones but it happens to both. So in the examples given above the programme which was an hour long I was watching from Sky+ and last nights TV was the football so that was live.

It does not seem to be affected by the length the TV has been on. The programme which was an hour long and had numerous issues was the first time the TV had been on all day.

I have called the retailer how I bought it off to explain the problem but I need to identify if it is a manufacturers problem or if its expected to happen. Personally I would have thought a TV costing £600 would be fault free for at least 2 years