G5 Won't Boot Off Orignial Cd


Hi, I have a 1.6 PM G5 w/ 1.25 GB RAM, nVidia 6800 GT, 80GB HD running 10.4.2. I have had problems with freezing and have checked every hardware component that I can (RAM, HD, Peripherals, Video Card) and they all seem to be functioning properly. I know there are many message boards commenting on G5 freezing, and even a faulty PM spotted (SP 1.8). I read on one that a lot of people started having problems when they moved to Tiger. Willing to try anything, I decided I would move back to 10.2 as thats what the computer shipped with and is on the original system disc. When trying to boot of this DVD, I can get to the white and grey apple startup spot and can hear the optical drive fire up. Soon after a grey screen covers the white background and I get a message that I have to restart by holding the power button down. I have tried holding down option and selecting the DVD and holding down C just to boot from it and all have the same outcome. I also tried booting off my iBook panther discs and the same thing happened. Please, any advice at all would be great! Thank you!
Have you tried the Tiger disk, just to see if it can boot off of any disk?
I thought I remember someone else having this problem, you might want to do some searching.
I pretty much have exactly the same problem with my dual 1.8 G5. I just bought it off of eBay and I don't have another graphics card to use! :( Oddly though, it won't boot up off of my Tiger CD or my Panther CD... When I try with Panther, I get the freeze up just like the other guy. When I try with Tiger, it just ignores the CD and boots up off of the hard drive as normal. Any suggestions would be appreciated! :D