I tried to install Ubuntu 11.10 from a Live CD and from a USB pendrive, but when I choose try Ubuntu or install Ubuntu from the boot screen, all I get is this message: "out of frequency range" and the monitor turns off in few seconds. I use an nVidea GeForce FX 5200 graphic card.
Have you tried booting it in "Safe mode"? I can't remember if the LiveCD has that option or not. If that doesn't work you may want to try to download and install from the "Alternative Install" Ubuntu disc.