When playing dvds on the computer tv loose signal

Hi. I got a brand new samsung hdtv connected to the secondary output on my gfxcard (using it as a secondary monitor instead of using normal tvout). Anyway my problem is that when i play a dvd movie on my computer and try to run it at fullscreen on my tv the tv loose signal and turns black , but when i play any svcd,vcd or xvid it works great in fullscreen. Anyone encountered this problem before? I have no idea to what the problem might be. When i used a normal scart before it worked great but now when using vga it doesnt work at all…

Would be a question for Samsung then, I think.