Try mapping the drives.
You'll need to know the network names of each computer and username/pass if the domains don't match.
I'm on XP, if you have vista it might be different steps.
My Computer -> Tools -> Map Network Drive
Pick a letter for the drive to have, then put in the shared path:
i.e. if the desktop's name is desktop and its shared folder is called shareddocs
you would put in \\desktop\shareddocs
If this doesn't work, there is something else fundamentally wrong - the folder isn't being recognized as shared.
(Ensure you have everything correct, though. A small error will result in it saying the path does not exist)