Thanks for the answer.
Thre seem to be a problem with the modelines generated by LMCE, each time I use them my screen goes black. If I swich to generic modes in xorg.conf (1024x768) my screen is readable again. This also is the case of the 640x480 modeline in xorg.conf.pluto.avwizard. It is therefore impossible to run the AVWizard. I have tried to cange xorg.conf.pluto.avwizard manually, but it seems to generate again. My linux knowledge is rather limited so I am stuck. Any ideas?
My TV is a Sony 50" projector LCD wich is connected with VGA (and also DVI to HDMI if I want) to av nvidia 6800 LE.