screen jagged when booting from dvd

[novapgh]

I have two problems. The first one has to do with changing permissions and I found a previous thread that said how to fix it. In order to fix that problem, I have to reboot from the dvd which get me to my second problem. When I try to boot from the install disk, the screen comes up jagged and keeps turning off and on. It looks like a tv screen with a lot of static. I can't read the screen at all.