Hey mate, I had the exact same problem, and been working on it for 12 hours until I accidently came over a solution..
at Ubuntu bootup menu (before installing) highlight "Install Ubuntu" and push F6 and choose "ACPI=off" then push F4 and choose "safe graphic mode" then it will work.. I tried installing ubuntu 6 times and messed around with all kinds of stufff.. until I accidently tried ACPI=off at the end of the kernel command line, that worked wonders.. but safe graphic mode and VGA=773 might also be of big help if you got graphic card problems..
VGA=773 then goes at the end of the kernel line (which shall be possible to easily edit before pushing enter in the Ubuntu install bootup menu (the first screen you see)..
Goodluck mate
For more information on this Ive written an own thread about just this problem: http://ubuntuforums.org/showthread.php?t=859692
Hope it works out for ya
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