Hi Ralf.
It seems that most people don't experience the same issue that I have and BS3 normally selects the right resolution straight off. You can check what resolution it is running at in the customer service menu under screen information.
This process is only of use if BS3 is outputting the wrong resolution for your panel.
1, Press menu on Beo4
2, Highlight options and press red followed by go. This accesses customer service menu.
3, Select picture adjustments
4, Turn "monitor auto detect" to off. This means BS3 will not try to look for a resolution from the panel but should go to it's default of 1280x720. You may lose picture at this point. I did and promptly shat myself. I then learnt two things. Pressing a different source button then brought it back. If you add reset as a command to beo4, turn off BS3 and then press reset it takes BS3 back to it's default setting meaning you have an escape route if you select a wrong res or something else goes wrong.
5, Press menu on Beo4 and select options, connections and then at the bottom under screen 1 it should say non B&O.
Select this and you then get several options including display resolution. (This setting makes no difference unless you follow step 2!)
6, Select your appropriate resolution from the list.
7, Set menu option "keep setting" to yes and you are done.
If your screen goes blank after you select resolution but before you change "keep setting"option then BS3 does revert to previous option after 10 seconds or so.
I did have one further issue which caught me out for a short while. After sussing out the resolution thing I selected 1920x1080 as the resolution but got no picture. It turned out to be the DVI-HDMI cable I was using. It was a inexpensive non branded one that was 15m long. Whilst it worked at 1280x 720 it wouldn't do 1920x1080. I changed it for a qed HDMI-HDMI with a DVI-HDMI adaptor and then it all started working.
I finally set up the picture with a "Digital Video essentials" test disc. With standard settings the image was quite dark and a bit over saturated but after calibration it was much better.
Please note that this is all information I have learnt by trial and error and it works with my system. I assume it would be the same for other panels but I can't be sure so anyone reading this should tread carefully as I can't offer any further info than is here already. Nor can I take resposibility if something goes wrong for someone else.
Hope this helps.
Geeze