reboots before getting install screen

Hi, I've been attempting to install beta 2 and so far I haven't had much success. On the machine I would like to install on the computer gets as far as the gui before the install now screen appears and then reboots. I've tried almost everything I can think of to get it to work. any suggestions my machine: gigabyte GA-8I945P p4 3.02ghz 1gb ddr2 ram dvd+-rw dvd-rom 2 sata 200gb drives 2 pata 160gb drives
I do not believe it is the dvd because I can get get to the setup screen on another machine, and I can install with vmware. help is more than appreciated