Leon, are you still having issues?
From reading your statement I have gathered that you want to save your images from your FOG server on a network space, is this correct?
I know that FOG is going to need access to this folder with read and write permissions, I would first start with checking there and trying to make a public space where it will not be affected but network policies.
We use a Novell Network here and I run into problems with permissions all the time.
However I am not familiar with adding a space for the FOG server to save an image to, in my FOG server there is a drop down box where I can select “default” and possibly a node if I had installed one. I don’t know what is involved with locating the space on the network and adding it to the drop down list.
I would also install the Samba service of Ubuntu to help alleviate some of the problems your going to run into using a Linux box in Windows environment.