Logic Pro 7 & earlier Logic 6 core audio driver not found


I have a G5 running OSX 10.5.8, and I have Logic 6, 7 and 8 installed. I can open Logic 6 but I get a message saying "core audio selected driver not found" and even though it opens, I can't get any sound. Also the MOTU interface I use doesn't appear in the audio hardware & drivers window. I'm trying to open some old project and they won't open in Logic 8, and I can't get 7 to work either at the moment (separate thread).