Home Forums Mac Software Mac Operating Systems How to reinstall 10.6?

My wife's 27" iMac 11,1 has been through the wringer having upgraded to Mountain Lion 10.8.5 and then downgraded back to Snow Leopard 10.6.8. I have an Apple installer disk containing 10.6.2. An external, tray-loading DVD drive is attached. We do not use the iMac's internal DVD drive due to scratching of the media.

I would like to re-install 10.6.2 from the installer disk and then upgrade it to 10.6.8 which is my wife's preference for now. I can boot the installer disk, but when I try to select the current 10.6.8 for replacement, a yellow triangle appears and I am prevented from doing the installation. Is there a way to get around this barrier? There are two other issues I need to address, but they may be solved if I can reinstall 10.6.2. They are: The Recovery Disk is shown as 10.8.5. This is a left-over from when she tried Mountain Lion and decided she wanted to return to Show Leopard until she finishes her book. The other problem is that there is an eDrive icon left over from a trial of TechTool Pro. We asked and received a refund, but I deleted TTP before using it to delete the eDrive not knowing that that was an incorrect procedure. I have been able to delete all the content of the eDrive, but I can't delete the drive itself. Unfortunately, I was again too pressed for time and did not read the instructions before acting.

We have her data backed up in time machine.

From all of the changes that have taken place, I believe it would be a very good thing to reinstall 10.6.2 and then upgrade to 10.6.8 and then retrieve the documents from Time Machine.

Advice would be deeply appreciated.

Yep. You can't just re-install an old version over a new version, you'll get the yellow triangle. In order to do what you want, you must first erase the hard drive.

When you boot from the CD, you should see a menu at the top of the screen. Under the "Utilities" menu you will find "Disk Utility." Use Disk Utility to erase the hard drive, then install the operating system.

Thanks a LOT! That really helps.

I have now also found a step by step procedure that goes into great detail:

See: http://support.apple.com/kb/HT3910

Thanks again!

OK. Things are humming along as the hard drive is being erased. 57 minutes of a two hour process are left. I selected to zero out the whole drive.

I intend to use the Applications Install DVD to install all Apple apps and to follow it up with Software Update to make stuff current. However, Time Machine shows applications as part of my most recent backup. I plan to restore from Time Machine for the documents, but what will Time Machine do to the wonderful new applications that I download before restoring from Time Machine? Will Time Machine recognize that the new apps have a later date than the latest Time Machine backup and leave the new ones alone or will they replace what was just done?

Thanks, Tacit, your initial guidance put me on the right track. I have been able to erase the entire hard drive and re-install Snow Leopard from scratch. It's now working like a charm, but we're concerned there might be other problems that can only be addressed by taking it to the Apple Store downtown. We'll keep going until we encounter other problems, if any.

The problem turned out to be a bad graphics card. The good news is that it costs half as much as the card on other Macs because it is removable from the logic board on iMacs. It's in the $240.00 range.