Mutsch from 'playstation-disorder' reports:
"Just recently a friend mine asked me to test a one of his DVDs on my PS3, cause his unit doesn't playback the DVD anymore. My first guess was that there is an issue with the upscaling feature of the PS3, but interestingly enough it is a problem with only a few DVDs.
First of all the DVD played as it should on my PS3, no problem at all. After searching on the net he found out that there is obviously a bug in the current firmware that causes the screen to go blind for some DVDs. the way to correct this behaviour is to switch the max resolution back to 720p use the DVD player and switch it back to 1080i or 1080p, whatever.
As it looks right now this bug was introduced with the 1.90 firmware as part of the upscaling feature. As you might remember I also experience a similar bug on my monitor that doesn't allow me to upscale both PS2 games as well as DVDs."