Thanks for that, however I don't think this is the cause. As I read the Apple KB article this affects client machines on 10.2, all of our clients are on 10.3.9 or 10.4.6, it is the server that is on 10.2.8 and it is fully patched with everything from Apple.
I am hoping that ArchiCAD 10 may solve all my problems!
Many thanks.