only half of install screen is displayed

I am new to Ubuntu but not to Linux. I have worked mostly on Red Hat and mostly at work. Anyhow, i downloaded 7.10 - i386 version and ran the check to make sure the .iso was good. When I popped the CD into my old laptop the screen came up and i selected the start/install. I then got to the desktop. However, this is where it goes wrong. I get half of the desktop on the top and the bottom is black. Below the are the specs on my machine:

AMD Athlon 1Ghz
256MB RAM
ATI Rage Mobility