Summary of problem
Gigabyte G31M-ESL MB
Dual Core E6300 CPU's
4GB RAM
Asus Nvidia 9600GT graphics card connected to 17" screen by Raaritan 4 port KVM on VGA port. I don;t have HDMI (sadly)

Black screen on boot after 10.6.2 upgrade. New sleepenabler installed.

Whilst it's bad form to reply to your own mail, I have made a rather interesting discovery.

1. I set the Energy Saver for the screen screen, not PC, to one minute.
2. Rebooted the machine and had the same black screen as I normally get after the update to 10.6.2. i.e. I can move the mouse but cannot see the screen.
3. Left the machine untouched for the requisite minute and the monitor clicked into standby as the Graphics card went to sleep. I know thats not the right phrase but hopefully you know what I mean.
4. Hit any key and lo and behold, my screen appeared instantly. No changes to kexts, uninstalls.

I think the black screen is related to some sort of power saving issue NOT the HDMI copy protection stuff that most people have looked at. Of course my guess is worth exactly what you paid for it, nothing

Hopefully this may help other people.