Aaargh. Thought I had this cracked, but guess I'm in a bit over my head. Don't know what I was thinking earlier, but:
I did what you suggested - dragged the iPhoto Library from the Pictures Folder to another Disk, and it copied 142 of the 170 Gbs to the back up disk and then stalled. I dragged that to the trash, emptied it, and started over only to get this message after 21Gbs in:
"The operation can’t be completed because an item is being modified."
I have these photos backed up in Time machine, so I'm no longer hyperventilating, but was looking for another safety.
Also, I now have two iPhoto libraries because of the iPhoto Updater thing I did. (see above)
Any suggestions?