Considering that, to achieve correct working of hdmi fed monitors from dvi output in windows you have to insert a registry EDID override. For nvidia you have to modify nv_disp.inf and add your edid override in there. I think this is so it forces it to use DVI over HDMI (switch off tv mode for that monitor)
Do you think that the monitor overrides on 10.6.3 are different?
According to this info, they are stored here in /System/Library/Displays/Overrides/
I think this is worth looking into. Without the above Windows Nvidia Driver fix my TV will not work in dvi mode over HDMI and i get a blank screen. Familiar?
Please can someone investigate this. Maybe backup the 10.6.3 overrides and replace them with ones from 10.6.2?
If you have a second machine, you can add a root password to your experimental machine and enable remote ssh connection in sharing, then if it boots into blank screen, logon remotely over lan to reboot, sleep or shutdown the machine. This way the drives are unmounted gracefully i think.
If you decide to sleep the machine, you can switch the cable to a dvi/hdmi to vga cable and wake onto VGA.
Anyway, I hope this gives you all some ideas
Good luck. Hopefully there will be a workaround soon. Might need a modbin!
Some Useful Links:-
anyone familiar with the nvidia edid override modifications knows that they change regularly in new driver revisions, forcing you to jump through new hoops!! Don´t upgrade a working system till you have to!!
link to a working windows fix for some 19x drivers :-