Ubuntu is way too popular for the ISO to become corrupted and no one notices. At what stage does the error message appear, while you're burning the disc or when you run it? Are you using decent blank CD's? Are you using 32 or 63 bit?
The error occurs when I try to load the disk. I burned it twice to make sure. It's the 32 bit version. Maybe the file I downloaded got corrupted. The blank DVDs are fine; I put the other version on one of them.
edit: I see now I should use the 64 bit version. 12.04 has QT I presume?
When you run Ubuntu click the icon that says 'Software Centre' and search for whatever you want to install, though you should get a basic grasp of how computers work before you try projects like this, it always ends in 'Linux sucks because 'insert easy to solve using Google problem here', im not having a go at you just after spending years on Linux forums it amazes me how people don't know search engines exist, thousands of them.
I've used Linux before as my main OS. Obviously I checked Google before coming here.