Ahha! Ok, how is the machine linked to your monitor?
When I link via a DVI to VGA converter to the VGA input on my monitor, I get a picture when the OS loads. It has a horrible green tint, but I get picture the whole time though.
When I connect the machine to my monitor via a DVI to HDMI adapter, I get picture in the PROM, but I loose picture as the OS starts to load and only get it back once the OS loads the login screen. (This is the link that I use normally, as it gets rid of the SOG problem.)
Therefore, when I installed the OS, using my current screen setup, I used the VGA option. As I loose picture as the miniroot starts to load when connected via the DVI to HDMI link. (I don't know why this is though!)
I therefore suggest that you try using a DVI to VGA adaptor. (My screen doesn't have a DVI input, so I don't now how it works with a pure DVI connection.)