Less chain noise?

Andy.w - The chainring, chain and rear cassette are all in good order, and reasonably new - I'm pretty sure it isn't that.
Basically, whenever i accelerate out of traffic lights, or I'm pushing really hard up hill (i.e when I'm putting it under a lot of pressure), something goes "BANG" and it feels like something jumps or slips. I cleaned everything really well, but it still does it?

Mine did that just before the Quicklink thing gave out. Worth a look see/swap for £3 or so if you have one fitted.