G3 iMac 400 10.2.8. I have an external firewire drive that I use for backups. this afternoon I booted from my copy of my hard drive on it, just to see if that worked, and it did. then I switched the startup disk designation back to the operating system on the iMac harddrive, ejected the disk images on it and unplugged the drive (in order to used it to back up my wife's laptop). when I tried to reboot the iMac - nothing. the power indicator light comes on, I hear a few clicks from the hard drive spinning up, a sort of a "sprong" noise that I associate with the monitor about to come on - but nothing happens on the monitor and no further sound from the hard drive (other than the whir that I assume means it's spinning).
any suggestions as to what is going on here - and more importantly, what I need to do to get back to functional. (I just started considering replacing the hard drive with a larger one and hope I didn't somehow offend my existing one!)
thanks - Roy