Q: mac os x v 10.5 trying to install snow leopard then upgrade to other versions having issues

Shut the Mac down.

Then wait ten seconds and restart while holding down the C key and inserting the disc simulanteously.

Just so you are aware, Snow Leopard v10.6 is a very outdated OS X. You may have issues using the Safari version that  runs on Snow Leopard such as not being able to access the internet, or slow loading pages, or Safari quits unexpectedly.

What Mac are you trying to install on?

10.6 requires an Intel processor - are you certain it has one & is not a Power PC Mac?

You can't boot a Power PC mac from a 10.6 install disc, so that could explain why it ejects.

If you can post the model info that may help.

http://www.everymac.com/mac-identification/index-how-to-identify-my-mac.html

Identify the model of your iMac - Apple Support

Apple probably have other help for other models or you could give us a clue…

That should work. That model can run up to 10.7.5 according to the app at mactracker.ca

We probably need to know what disc you are using to try to boot it? Is it a grey disk or does it have the Snow Leopard printed on it? Can you see a version number on the disc (small text with a full version like 10.6.3)?

If Disk Utility is failing mid verify it indicates your disc may be faulty or damaged. You may need to find another install disc set in that case. The CD/DVD drive is otherwise working? Is the disk scratched or dirty?

Note: You must update to use the App store on 10.6, you can get combo updates to go to 10.6.8 via software update if it can be installed. You also need 10.7 in your app store account or purchase a copy & download via the store…

http://www.apple.com/shop/product/D6106Z/A/os-x-lion

I think the options you have are…

Try another set of install discs for 10.6

Make a bootable 10.6 or 10.7 installer if you have access to another Mac, this may be a Firewire or USB disk.

That all seems correct to me. The white disk is a 'retail copy' intended for all models so it should work.

Insert the disc, reboot, hold 'alt' (a.k.a. option) at startup. See if the disk appears in the list of bootable discs. Click the disk if it's an option.

What happens when you reboot & hold C at startup - you may need to wait many minutes with the key held down, some CD/ DVD's can be slow to load. Eventually it should load the installer.

Another thing to try is to boot into 10.5, open System Preferences > Startup Disks, select the Snow Leopard install disk & reboot. If it fails to work go back & change the setting back to the original OS disk in the startup disks list (otherwise it will have to search for an OS disk on startup).

Do you have access to other Macs?

Hmm, the 4,1 Macbook has 2 possible optical drives - a CD combo drive (that should read DVD's too) or a CD+DVD superdrive. Both should be able to read the disk from Apple.

Can you boot into the old OS & view the disks contents in Finder?

What have you downloaded? I'm not sure what you mean.

Ah that makes sense now at least the disk is readable by that Mac - the disk should work. Many of the files may require 10.6 to open but there may be a read me pdf or text file that you can view. Take a look in the 'Instructions' folder and view a one of the PDF files a test.

I'm not sure what to suggest, the disk should work. Where did you get the disk from, was it from the Apple online store or somewhere else?

Does it appear in 'System Preferences > Startup disks'?