I tried it last nite, it still happen, and I found out if I choose 'Pure Audio', the noise is even louder.
I guess that why when I WATCH bluray, it is fine, coz it has video output.
I think there is not much I can do about it for now then...
I really don't know, I guess it has something to do with my wall socket. I was trying to turn on the projector and see does having video output help, but once I pluged the cord in without even power the projector on, the noise is gone.