Unfortunately, thats not much info to work with.

Obviously it is server related... though they will deny it black and blue. it will be some kind of permission or setting they don't have activated.

In my experience many server admins aren't all that familiar with windows web servers as they are not used all that often. The vast majority of web servers are linux based thus they stay clear of windows server issues unless they have no choice. I'm sure most of their Zen cart clients are on Linux servers and don't have this problem.

Though it might be a little painful is there any reason you need to be on a windows based server?

You can prob swap for free if you speak to go Daddy.