mmcfee

As a final confirmation, I got a new Mini today and tried the same 10.5.6 disc that the Core i3 iMac would not boot from and the Mini readily booted it. So I assume, unless some magic happened in the 10.5.7 DVD, that this Core i3 simply will not boot 10.5 of any sortl (from DVD nor cloned drive). Guess I should grab a couple of Minis while I can for fail-over.

My issue is specific to the iMacs so far which have Core i3 processors. The Minis still have Core2Duos and I suspected that they might run 10.5 of some flavor. I've ordered a Mini, actually, just to confirm this. Looks like you beat me to it. As for the Core i3 (and 5 and 7), they must surely use a different chipset than any previous model, so my suspicion is that this is at the root of the problem. I'm going to try to track down a 10.5.7 or 10.5.8 (was there one?) DVD and give it one more try on the Core i3 iMac I have.

Just joined up to say "ditto" on this thread. We run an all Linux/Unix back-end and have single sign-on (for Mac, Linux & Windows via LDAP, Kerberos, NFS - plus SMB for Windows boxes). Some of the changes made in 10.6 mean new machines simply don't work in our environment. Which is sad, because we were excited when new machines running 10.5 recognized they were in a shared environment at first startup and would automatically attempt to join our 'domain' (for lack of a better word). We thought "Hey, Apple is starting to pay attention to the shared environment 'enterprise' space. But now... all of that has changed completely. All sorts of small steps sideways or backwards have made 10.6 unusable for us. Local unix groups in 10.6 don't stop at GID 99 any more (encroaching on existing groups), the Finder freaks out at auto-mounted NFS home directories, Apps won't launch due to lost group permissions, and so on. So, until we work out how to overcome all this without tearing 10.6 apart and get 10.6 machines to work, we simply can't buy any new machines. Sorry Apple. Thanks for trying back in 10.5 to play in the 'enterprise' space... but no thanks for then just throwing it all out again in 10.6. We're stuck in a Catch-22: We can't install 10.5.x on new iMacs, new iMacs with 10.6 won't work in our environment (until we pull it apart and find out everything that's changed). Maybe 10.7..... ?