When a folder is copied from one place to another whether it's from a server to a client or from a client to different location on a client, the ownership of the folder changes to that of the user that did the copy. Moreover, the permissions on the folder change to the preset umask. (usually 755 for folders.. Owner - rwx, group r-x, everyone else r-x.
While this is not what you want it is behaving properly.
What you need to do is to have your users get info on their folder after they've copied it and set the "everyone" permission to read and write. Or better yet show them how to add users or groups to the acl of their folder.
It seems like a hassle, but imagine the security implications if users folders were by default, read and write access by everyone.
Alternatively You can defeat this problem by having users NOT copy the folder back to the server. Just the excel file. When they're done editing it, have them save it with something different as a name that represents a revised file. Then copy it back to the server by itself.
You'll end up with a folder full of excel files, but it's not so bad considering the version history record!
Hope that helps!
-Graham
