I have been having an authentification problem with ARD.
I have been using VNC but treated myself to a copy of ARD and I am very impressed with it.
However a few days into using it I stated getting Authentification problems:

NOTE:connecting to a machine running OSX server 10.4.3 from a workstation running 10.4.3.

I would double click on the machine as usual and I get a "failed to authenticate error message"

No settings were changed, the ARD client settings on the server in sys prefs are set to full rights for an administrator, and the administrator user name and password were being used for authentification.

All of a sudden it has stopped working? any ideas why? the only thing i was thinking about is if I have had VNC running on this machine in the past could there be some sort of conflict going on in the background?

Network connection is fine.