Reinstallation issues

So I've got this old iMac G5 I want to use again, but it's got so much crap on it that I don't want to go through to clean it up, so I figured I'd just reinstall a fresh copy of Tiger on it.

I've got the installation discs that came with the computer and when I put them in and restart (either from a restart/turn on and holding C, or a restart from putting the disc in when the computer is on and clicking the restart button on the software) it will load with the gray Apple logo screen then it will go to a blue screen with a mouse pointer that I can move around (I assume it's loading the installation interface) that quickly turns into a spinning beach ball. The computer then shuts off and I have to manually turn it back on and hold down the eject button to eject the CD. The computer will start up, run and work fine after that.

And ideas? Thanks.

Offhand, I'd say it either doesn't like those install discs (they are for the G5 platform rather than Intel, right?) or the CD drive has gone bad. Can you read those discs or others when booted up normally?