I have a similar problem, I just put 8.04 32 bit on my XP box with an ATI 9500
series video card and it locks up whenever I try and change the screen saver.
Actually it locks up as I'm selecting and previewing the different sceen saver
choises.

I just tried a live CD of 8.04 64 bit on a Vista box and the display flickers
badly, Samsung 2253bw.

I wasn't expectimg video driver problems, but both machines are experiencing
video display problems although they are somewhat different.

ATI has not been the most Linux friendly vendor by far. It may not help your
situation, but it keeps things in perspective. i.e. Don't blame Linux distros
and avoid ATI until they clean up their act.

I have Nvidia on my other computer, when running Live CD 8.04 the display
flashes constantly.

Any advice on that?

I'm not giving up on Ubuntu, I still use it all
the time. I'm just a little pissed at ATI for dropping support for
their legacy equipment! Here I have this nice laptop that, albeit 4+
years old, still works great and, under Win XP (it's dual boot),
provides very decent graphics & effects. I'm just jealous of everyone
else out there that's able to at least have the compiz cube (which
worked on this laptop when I had 6.10 running on it). I was just hoping
somebody out there had some type of "fix" for my problem that I hadn't
seen in the forums yet.

This isn't stopping me from using Ubuntu everyday. It's just bothersome
knowing I have a video card that can do most of the neat "eye candy"
things but, because of a lack of a good driver, it never will. Guess
it's time for me to stop being so cheap and go out and get a new
laptop!! Of course, it'll have to have an nVidia card this time!

Try booting in a different resolution. On the initial boot screen you can change
the video settings at the bottom. I think that it is F4. You may have to try
more than one. If this does not work then you may have to change the boot
parameters on the bottom line to vga simply by typing in the window below the
list of options. To do this you add something like xdrvr=vga.

I played with the ATI divers, reinstalled them, and it seems to be
working very well at the moment on the XP Pro box.

Very nice, I now have a machine that I can use to start exploring linux.

I would like to do the same thing on the Vista box, but because I'm having so
many other problems on the Vista box I'm thinking about putting XP Pro on it too
and then installing ubuntu.

People should leave Ubuntu if it is Ubuntu that lets them down. Before they do
leave and give Ubuntu a bad name in the process they just need to be sure whose
blame it is which was my main point.I am not an Ubuntu evangelist and I will
jump ship as soon as something lets me down or rubs me the wrong way, like
anyone else.

In some cases Ubuntu makes compromises to cut things so that they can continue
to use a CD instead of the larger DVD format used by some distros. A DVD would
allow them to include everything but kills bandwidth and therefore reduces
access for some. Other times it is the fault of the OEM, not playing ball with
Linux, and rarely, but it can happen, it is the kernel developers who let us
down. In many cases it is a combination of factors.

Ideally it is best if the community can get unhappy users back on track, but
sometimes we need to be prepared to recommend another distro.

I know this is kind of old but, I just thought I would let all
know what I did to solve the problem with not being able to run Compiz
on my laptop (which uses an ATI Mobility Radeon 9200 graphics card)

It took a lot of time (seems like it anyway) going through the Ubuntu
Forums but, a similar problem had happened to someone before and, this
is what that user did to fix it.

Using the open source drivers supplied with Ubuntu, all I had to do was
create the following config file to my Home folder:

I typed the following line in a text editor: "SKIP_CHECKS=yes" (without
the quotation marks)
and saved it in my home folder as ~/.config/compiz/compiz-manager

I then tried turning on desktop effects again and WOW!!! I had wobbly
windows and everything! Almost everything in Compiz works without any
problems or apparent slowdowns to my older laptop here. As a matter of
fact, it feels brand new again!!!

Anyway, I just want to say that if your having problems with something
in Ubuntu, don't give up! Keep searching the forums (when you have the
time) and chances are, you'll eventually come up with either a solution
or a resounding "No, that ain't gonna work". Hell, you might even learn
something and figure out how to help somebody else!!