XP Network Access to a unix box

I have run up against a strange problem. I am trying to map a drive on an AIX unix box which gives all authenticated users the right to use it - which I can do. However, I can see the drive but the DC or whatever will not let me in - it says I do not have the proper rights .....
I can log onto the same box as the local administrator and map the drive(s) with no problem, once I seach for them and then map them. Even as THE ADMINISTRATOR I cannot map to them???
I seem to be not able to map the drive when I am logged into the domain but as the L Admin I can. That does not seem to make sense and how do I fix it?

John