Won't boot from disc...

Question

I'm running a less than a year old iMac with 10.5.8 currently installed.
I've been trying multiple times to install SL but the disc will just not stay in the drive to be booted from.
I've tried entering the commands to force the computer to boot to the disc on restart and I've also tried installing from the disc while being booted up.
It is almost as if the computer doesn't think its an install disc when it restarts, am I approaching something wrong here?
Thanks.

Answer 1

That will be a puzzle. It could mean that the disk is not working perfectly and that error correction routines don't work as well in the installer as they do with a working OS.
On the other hand, being able to restore the DVD to a drive from a working OS may also be possible with a less than perfect optical drive due to the OS re-reading data with error checking until it get's the data right.
I've gotten some optical drives to work pretty well by just using a 'cleaning disk' that you can buy from a electronics store for about $10.
It seems like drives on which I've had to use a cleaning disk do work for a few months, but then fade away and eventually need to be replaced anyway.
So, you can't go wrong with trying to get a replacement disk, and keep one eye on the optical drive itself.
Meanwhile, for me, I keep many installer disks as bootable partitions on a 250GB external FW/USB drive that has quite a few partitions on it. Hard drives are much faster for installing an OS or running a boot diagnostics or repair disk, and I never scratch my disks.