Leopard Server 10.4 Blogs/Wiki and Safari error with www alias and Log Out

Question

I have a Leopard Server 10.5 setup with dns and web services including blogs and wikis setup. If I browse to http://hostname.domain.com/users using Safari 5.0.1, I see that the session is not logged in (i.e. Log Out is not visible. I can login and create a blog and logout with no issue. I can do this on Firefox and Camino as well.
Now, if I browse to http://www.domain.com/users however... the Log Out button is visible all the time in Safari 5.0.1 only - Firefox and Camino show the correct status of a non logged in session. In Safari 5.0.1 it is not possible to login to post or create a blog WHEN the www.domain.com url is used.
I have rebuilt Leopard server twice on a physical and a virtual machine for testing and can reproduce the exact same error. It's a mix of using www.domain.com and Safari. Any other browser works fine and ALL browsers work fine with any other alias pointing to the same site, including hostname.domain.com
Testing on Safari 5.0.1 on the server itself works fine. Testing on clients was on 10.6 and 10.5 and was performed on 4 separate client machines. Browsing on the server was fine but browsing on any client would produce the error when using www.domain.com.
If anyone can offer any suggestions, please help!

Answer 1

I tried several new approaches, but nothing worked so far.
The update to 10.5.5 made things worse. Connections are dropping all over the place, when saving from Adobe programs in particular.
Printing from clients to a Xerox Phaser 5500 works, but choosing a different paper size than the default chosen in the cups admin interface goes all wrong and either prints on the default paper size, but down/upscaled to the chosen paper size or prints on the chosen paper size and down/upscaled as if you were printing to the default paper size. (e.g. default paper size is A4, you choose A3 with an A3 document. Document prints on A4 and is downscaled to A4, or prints on A3 and is downscaled to A4.)
There is no way I can keep this thing in production much longer. I tried reinstalling again, but that did not change any behaviour. Another nice "feature": InDesign disables "edit original" when the path to the linked file contains any directoryname with more than 8 characters in length.
Coupled with a sometimes disappearing "dirserv" (it just stops working until I reboot the whole computer) the decision stands to move away from the Xserve.
Leopard Server 10.5.x just does not seem to work well with windows clients.
We will migrate to a windows server 2003 running ExtremZ-IP for the macintosh clients this weekend. Too bad that Apple does not allow Bootcamp to work on Xserves, at least the hardware would have been useful then.
(As a nice finishing touch, the harddisk partition where all data resides did become corrupt over the weekend. "The volume Daten could not be repaired."
Disk Utility and first aid did show nothing on friday ... saturday after no work being done on the partition this error shows up. The only solution I could find was to reformat the partition and restore from a previous backup. Another weekend down the drain. Sorry for the rant, but 6 weekends in a row is enough.)