Startup problem OS 10.2 and G4 450 AGP

Hi,
I was running OS X 10.2 on my G4 450 AGP for about a month with no problem, then it stopped mounting the harddrives. Apple tech support told me to do a clean install, which I did, but now I can not even boot in 10.2, I get a grey screen with a grey apple, and a band of white vertical lines through the middle (then it freezes). I updated the firmware, and took out an aftermarket superdrive (AO5), so everything is original.
I have 896 megs of ram, an 80 gig 7200 ATA harddrive (partitioned and set to slave), the original 20 gig ATA drive (set to master, which is where I am installing 10.2), and a 2 gig SCSI drive (which has 9.2.2 on it). I can install and run 10.0.4 with no problem. I think it is a damaged file on the 10.2 cd, but Apple insists it is a hardware problem, and won't replace the cd. I can't see how it could be a hardware problem if it was running well before. Anythoughts? Thanks, Linda

If you boot to 9.2.2 can you see all disks mounted.

If I am reading this right you have a master disk at 20GB, a slave disk at 80GB and 2GB scsi disk. The only disk you have partitioned is the 80GB disk?

Here is what I am trying to understand. The 20GB disk is where you installed 10.2. Where did you install 10.0.4? Did you do a clean install and in 10.0.4 on the 20GB disk?

What I am looking at is a bad disk drive, I am trying to get an understand of what was loaded where and what worked.

G4 450 and OS 10.2 problem

Thanks for your response.
When I boot up in 9.2.2 I can see all three disks (the 20 gig, the SCSI, and the 3 partitions of the 80 gig). I did not partition the 20 gig, should I? When I've done the clean install it has been over the 10.0.4 (Apple told me to do this, that I shouldn't leave both systems on incase the conflict is there). Also, I have tried installing 10.2 on a 8 gig partition of the 80 gig drive, keeping 10.0.4 on the 20 gig, but got the same start up problem. This is why I think it is a bad file on the install cd, since no matter which drive or partition I've installed it on, I get the same crash.
Thanks again, Linda