samba - Jun 2008 - Problems with Windows Offline Folders / Samba

Have recently installed Ubuntu 8.04 and using it as a file server for a 
small office with Windows XP clients. Am trying to use Windows Offline 
folders on a number of laptops, but keep getting error messages when 
users try to sync when rejoining the network - something like "cannot 
synchronize test.txt, access is denied on //server/share/test.txt".

The users are all able to read and write files from the server once 
connected. It seems like only files which are changed or created when 
the user is offline fail to syncronize.

I've read that this is something to do with access control lists, but 
I'm not that familiar with Samba, so any suggestions as to what I can do 
to put this right? I thought I'd managed to enable ACL, but I'm not
sure.

Thanks

Russell