When booting from an Ubuntu/Kubuntu 6.10 (Edgy Eft) Live-CD/DVD for i386 or for
AMD64, either normal "boot and install" or "safe graphics mode", with or without
various boot parameters, the screen always turns black and stays black and the
computer freezes at that point of the boot process when the GUI (Gnome/KDE)
should be starting. It is not possible to get to a text console by pressing
Ctrl+Alt+F1 (nor F2...F12). The only thing one can do is reboot with Alt+SysRq+b. 

My processor is AMD64 and my graphics card is "ATI Technologies Inc RV350 AP
[Radeon 9600]". 

There are two workarounds: 
1) Boot with break=bottom, the (initramfs) prompt comes up, /chroot root, edit
xorg.conf with e.g. nano and disable the module "dri" by commenting out that
line, save and exit nano, type exit at the boot prompt twice, the boot process
continues and the GUI comes up, everything works then.
2) Alternatively change the AGP speed from 8x to 4x in the BIOS (if it's an AGP
card, not a PCI-E card). Then it is not necessary to do anything special, the
normal "boot and install" option works right away. 

This is a confirmed Ubuntu bug for ATI graphic cards:
https://launchpad.net/distros/ubuntu/+source/xserver-xorg-video-ati/+bug/67487

Some people with NVidia cards reported the same problem, but other people said
that they probably experience a different bug. 

Most people that reported the bug seem to have AMD processors, but at least one
of the persons had an Intel processor.

Here's the xorg.conf and Xorg.0.log that I received after commenting out the
modules dri and glx (it turned out later on that it does not make a difference
if one disables glx or not): http://librarian.launchpad.net/5217493/xorg.conf
http://librarian.launchpad.net/5217508/Xorg.0.log

If it's useful, I can also get the Xorg.0.log when only commenting out dri and
not glx and when booting with AGP speed 4x and not making any changes to xorg.conf.