well, to start, how many buffers are you using? createBufferStrategy(1) will still flicker
In my "adventures" with BufferStrategy and it's ilk, I've read through the code for both Component implementations of BufferStrategy and at least FlipBufferStrategy won't let you use less than 2. I'm not sure about Blit... I guess he can't be using 1 buffer if he's using flipping.
Maybe, if he's using active rendering, his paint method is still being called and that could have something to do with it. Probably not.
We need more info, is what.