I too have a problem with the DVI output from my Mac mini G4. I have the 1.42GHz 32MB VRAM model.
What I have discovered so far is that is seems to have a problem with 1920x1080p displays. I used to have a 37" LCD HDTV that it never worked with. I only ever tried straight DVI-D with it, even though the TV also accepted VGA with an adapter.
Fast forward to today and I have another 1080p monitor I am trying to get it to work with. This time an HP E27i. The monitor has VGA, DVI and DisplayPort inputs. I plugged the mini into the DVI and I get no display. It *does*work with the VGA adapter on the mini. There are a couple of problems with this, however: 1) VGA output is dimmer from the mini G4 (a known problem I believe) and 2) The HP E27i seems to have trouble sensing a signal from the VGA input. I think the monitor is faulty in this regard. I can get the image to display if I hit a button on the monitor. This is not ideal of course.
The really funny thing? The mini works fine over DVI with two other monitors I have. They are both 1900 x 1200 displays. Does the mini not like 1900 x 1080 over DVI? Maybe I will try reducing the resolution and see if that makes a difference.
