Flashing folder icon with question mark.

Take out the HD and attempt to boot from CD... in fact sometimes if you put the install cd in and boot the machine should choose it on it's own... unless the CD is damaged, or, sometimes has an older system on it than what you were currently using.

I am not able to install the iMac's hard drive in an enclosure as I do not own an enclosure. As I mentioned I did put the iMac into target disc mode, connected it to my MacBook pro via a firewire cable, and could read the start up DVD that was in the iMac but not the hard drive that was in the iMac. I did disconnect the cables to the iMac's HD and inserted the start up disc while holding the C key down and nothing, except flashing folder and question mark. The start up DVD is from my MacBook, I assume it will start up from that. Thanks for the help so far.

Sorry to say the recovery CD/DVD you got from your MacBook Pro most likely won't work here as your iMac G5 is a PowerPC based system were as your MacBook Pro is Intel based. The OS's needed are very different from each other. At this point you would need a OS-X Snow Leopard (retail version) to boot up your iMac as it has a fat binary (the OS has both kinds of files).

Agreed at this point the install CD is not compatible with your machine... I'm surprised that a message stating that doesn't appear on the screen of the iMac (often it does)

Thanks to everyone for your help. I did find an enclosure for the hard drive. I removed the hard drive from the iMac G5 and installed it in the enclosure and could not get it to fire up, so machead you are right, that hard drive is dead. I also found an OS X Leopard disc and installed it, held down the C key and it promptly booted up. So I have a new hard drive on the way and will do a fresh install and see what happens. Be back in a couple of days.