OK, taking another look at my booting problem (where the computer sees neither optical nor hard drive, though both work perfectly fine in target mode): It has now become apparent that a firmware upgrade was started on this machine (before I got it) and it was corrupted. For example, all conventional keyboard commands in start up mode (open firmware, c key, option key to select drives) do not work. so I downloaded (from Apple) the "firmware restore cd 1.4 for Imac 5,1" (my machine) and happily set about to install it thinking i had the solution to my problem. Followed instructions exactly (burning the .dmg to a cd disk, inserting with power button held to trigger firmware update/install mode). Computer went into firmware update/install mode but -- refused to spin the disk in the drive! just "ca-chunk ca-chunk" ad infinitum. Of course i want to fix this myself, not pay apple $800 or so (assuming it is fixable). Any suggestions on how to get this firmware restore CD to load? Alternatively -- will the computer automatically boot from an external firewire drive even though it sees no other disks? (certainly works fine when in target mode) Please contribute your experience!!