Comment 28 for bug 542660

I am having the same problem, I have a "iMac 27 2.66QC/2X2GB/1TB/4850 - 512MB/SD/WLMKB"
I put the disk in, install it in windows, reboot, black for a long time as it instills ubuntu, then reboot's again, then black screen the hole time, stop's loading but still a black screen, So I press Power button and it tunes off,

I start again and press ESC, type : radeon.modeset=0 nomodeset

I type exit, enter, black screen,

This problem need's to be fixed, I was just trying to see what it look's like ?