This has something to do with HDCP since it is propriety with NV and WMP , I think Cyberlink also jumped onto their bandwagon....
It's basically simple cut throat capitalism, if you want the optimum benefit of common day tech, you need to use their products.....
But in anycase from the pic in the earlier post, I can say there is a tab in the cyberlink PDVD panel which disable split screen, it's like a comparison thing, I really don't know why they ever had it there, but it's comes alive after you have enabled HW Acceleration. Under it you have two other types of accelerations for improving the image quality, I think you've got the wrong one ticked.
Try fooling around with the settings there and it'll go.
Actually it's been ages since I used PDVD, I have it but somehow always find it more enjoyable to watch after ripping my content
I don't know about the settings he was using at that time either
But this sort of a picture I get when I use PDVD.... with the HW acceleration enabled
Hope fully, I'll get home in the next few hours and check it out with the WMC and post a reply later.....
I have experienced the exact problem you are describing to a tee, with a HD4870.
It seems that playing with the dynamic contrast setting in the CCC fixes the issue. (for me turning it off instantly fixes the problem)
Current problem I am having though, is that for some reason, it switches itself back on.
I notice it almost immediately during video playback, open the CCC and sometimes the checkbox is ticked again, sometimes its not, either way, i just toggle it on, hit apply, then toggle it back off and hit apply.
Usually fixes the issue for awhile. I am not certain, but I believe some program I use somewhere is whats toggling it like that, but have yet to figure out which one it is.. ( I use alot of different kinds of media players, and video editing programs)