I have ApogeeX clients installed on several G5's and they work great. I've got one client that doesn't work at all. You can log into it, but no jobs appear and no icons show up in any of the windows. We've called TAC, but they didn't help.
Make sure you have network access to the folders with data. Have you created account? Do you have access to it?
The G5 that isn't working is it upgraded from a previous computer, so that it may have inherited network buggs?
You need to create a host file on the mac, put the name of your server and your mac in the host file. Then you need to create a host file on the server with the name of you mac.
I had the same problem, the host files fixed this.