Well 10.5.6 did my iMac in. I have finally been able to get into terminal throught the Tiger boot disk that it came with. The OEM Leopard disk is just an upgrade and not recognized as a boot disk. What can I do from this point in order to either roll back to 10.5.5 or to boot using some basic configuration. I don't know the commands to switch to the computer's root directory. The terminal reads -bash-2.05b#. Can I save my system or do I need to start over with installing Tiger and then updating to Leopard disk that came with my computer. There must be something that can be done to get past the blue screen. Also, when I tried to boot using verbose, the error message was "importer start failed for 501. invalid destination port. Help would be greatly appreciated as I did a partial backup before updating to 10..5.6, but I still have important files on board that would be critical if I lost them. Thanks in advance for your help.