IMac will not boot from Snow Leopard DVD or original Leopard disc!

Question

Hey,
I am going mad! I am trying to update my iMac (with original Leopard installed) to Snow Leopard. Here is what I have tried:
Using the Snow Leopard DVD:
- A standard install: the disc ejects after about 15 minutes.
- Put another working DVD in and verified it in Disk Utility, all ok.
- Verified the internal hard drive in Disk Utility, all ok.
- Verfied the SL DVD, all ok.
- Decided to try a clean install, so backed up everything.
- Tried to boot from SL DVD by using the Utilities option, it ejects the disc at restart.
- Tried to force it to boot to the DVD by restarting and holding the C key, it ejects.
- Restart holding the Option key, it ejects.
- Restart holding the Ctrl, Alt and Option keys, ejects.
- Everytime it ejects and starts up normally.
- So I cleaned the disc, updated all the firmware, reset the NVRAM/PRAM via holding keys when restarting, and repaired disc permissions.
- Tried to force it to boot again, ejects.
- Tried to put the disc back in straight after it ejects with all the steps, still starts up normally.
- Changed the start up disc in System Preferences to the SL DVD, restart, it ejects.
By now I am readying the noose...
- Dug out the original Leopard installation CDs.
- Repeated all the forced boot restarts (C key, Option key, Ctrl, Alt, Option keys), same story.
- Repeated changing the start up disc in System Prefs, same story again.
- Call Apple Support, they told me to try everything I have tried and that the DVD drive is dodgy, well it works with everyhting else! Burning and reading! I really don't want to have to go to an Apple Store- it's miles away (a costly journey) and I just do not have the time for all of this.
RAWR! Does anyone know what to do? Please? S.O.S.?

Answer 1

Possible scenarios:
1: The 10.6.3 SL retail disk is bad, it happens.
2: Your not using the 10.6.3 SL retail disk but one from another machine which doesn't have the drivers for that machine.
3: Your optical drive is funky or some other hardware issues.
4: Your trying to install 10.6 onto a PowerPC based Mac, no can do.
5: Your not using a wired keyboard for boot key commands, have some other hardware conflicts.
Possible solutions.
1: Copy the SL 10.6.3 disk using Disk Utility to another DVD, the error checking may resolve the original disk's issue.
http://www.brokenhomeboy.co.uk/pierow/blog/2011/10/make-a-bootable-backup-snow-l eopard-install-disc/
2: Make a SL bootable USB
http://www.maciverse.com/install-os-x-snow-leopard-from-usb-flash-drive.html
3: Call Apple for a new 10.6.3 disk (and make copies for backup before Apple discontinues selling it)
If your upgrading to 10.6 to get to 10.6.8 to upgrade to 10.7, be warned of this:
1: Your 10.5 software will not work in 10.7, no more Rosetta or PPC based code.
2: Your hardware will not qualify if it's a 32 bit Intel Core Duo, also you may experience slowdowns in performance over 10.6 (10.6 is the fastest OS X version for Intel Macs) in older Intel hardware (I suggest Early 2011 Mac's and later only for Lion)
3: Mountain Lion 10.8 is reportingly coming out this summer and will not run on a lot of older Intel based Mac's because of heftier graphics requirements.
4: 10.6 has the widest range of current avaialble software and drivers for third party hardware.
My advice, stick with 10.6.8 and stay there, buy a new Mountain Lion machine after this summer. Skip Lion completely.