Not to offend anyone, but I can see no excuse for staying with OSX10.2.4! 10.2.8 is the last free update to 10.2, and should be applied to all professionally used Macs, in lieu of shelling out the small change needed for the much better 10.3.
I would also guess a permission problem. Archicad is trickier than most programs with this. It has happened to me that Archicad refuses to update a file who's Owner changed, despite the file still had full read and write access for Everyone.
And Apple has also had issues in this area. My impression is that OSX took a long time to mature, and 10.2.x had small changes in every version. The file system wasn't complete until 10.3 finalized journaling, for example. So, always update to the latest system version after lurking a week on Macfixit.com to let others find the bugs.
First, do a Combo 10.3.8 update on the server.
Then, do a 10.2.8 Combo update on all mac clients unless you have knowledge of specific issues that prevents this. (Then, migrate to 10.3 ASAP. (10.4 won't mature until sometime this fall.))
Repairing permissions with the Disk utility won't help, because it doesn't do anything with user's documents or folders.
After doing a full backup and system clean-up on the server (clean caches, run maintenance scripts etc, perhaps with a third-party utility like Onyx
http://www.titanium.free.fr/ ), and you're sure the server is in good shape, you might try changing permissions on a test user. To avoid writing Unix batch scripts, use a program like Batchmod
http://macchampion.com/arbysoft/ . But use it slowly, taking care to read each dialog and warning through before applying any change. It will let you change Owner, Group and file priviledges on any file or folder and any combination of those. You can for instance change every file's read/write permissions in any folder in one step without changing the files' owners, even if they differ.
If you find this won't work, test re-creating a user on the server. you might then have to restore all files on this user account from the backup. Do this test for both a PC and a Mac client. This has cured problems with access from PCs to OSXservers I know, especially when migrating from Windows 2000 to WindowsXP on the clients. But shouldn't be necessary for the Mac clients if they are properly updated and maintained!
If nothing of this works, I'd go to Apple's OSXServer support. I'm convinced that is where the problem is this time, since you have the issue at all workstations.
But still, once you've scraped together the pile of money necessary for an AC9 upgrade, you'll find it's worth it. With such a large installation, i'd advice you to get bank financing. Even if permissions issues might surface still, you'll find that the productivity increase you get from 9 will easily pay for the bank interests many times over. This is not just because it's faster and more stable on the macs. it's primarily because AC9's tools are so much better and smoother in so many small aspects that add forcefully together - on both platforms.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1