It could be because a piece of hardware in the machine and Ubuntu don't cooperate well. Just a guess, but that's where I would start.
When you start the Ubuntu desktop/live-cd, and enter the boot menu, select the option to modify the commands before booting (or something close to that - anyway, the option which shows you the kernel line, where you can add, remove and modify the options). Then add this to the list:
Hit Enter and try to continue. If it works, you're going to have to add the same thing to the kernel line of the installed Ubuntu, at the first boot after the setup is done. If it doesn't help, you can also try these instead (one at a time):
As it seems, the error message you gave may be caused by a lot of things, and this is just guessing..