Display fuzzy

[gary65plus]

I'm new to Ubuntu, I have installed it on my computer. When I start it up it goes to the home page. butt, it is all screwy. On the sort of purple page nothing else comes up, All I get is the purple page with some black squares, and they change after I hit a key, but it is not acting like it is suppose to. My download is ubuntu 12.4? I have tried 3 different install discs but with the same results. Any suggestions
Thanks

[newb85]

Do you know what kind of graphics card you're using?