Thanks much!
The noise comes out of the speakers and TV. If I turn off the speakers, the noise still comes out of the TV. That's why I initially thought about audio set up, but tried all combinations and didn't work.
I followed the manual and connected the samsung directly to the TV via an HDMI cable. So there's one single HDMI cable running from the samsung to the TV's HDMI port. I have a Sony LCD 40 inches 1080p, about a year old. The bose speakers are connected directly to the TV. This is one of the bose systems that include a couple of speakers a subwoofer and a tiny thing (don't know how to call it) that's connected to the TV via red/white cable. This is the link to the speakers I have.
Bose CineMate GS Series II Home Theater Speaker System - Bose 2.1-channel Home Theater Speaker Systems
Sound/picture quality are awesome and when playing a movie the sound is extremelly good. It's only when I press stop that the sound starts and doesn't go away until I turn off/on the samsung.
Many thanks for your help!