Environment: Server 2008 and Windows 7
Problem: Some machines cannot see some files or folders on the fileserver
First occurrence: We were distributing new forms and wanted to make it easy so I went to the file server and copied the new forms folder into everyone's users\name\documents folder on the server (all of the user profiles are sync'd on the server). Some of the users could see the folder in their documents library and some not. Tried from a client machine to place the folder there and nothing happened, no error and no folder (assumedly because it already existed there although it didn't show). Copied to the desktop, renamed, and placed the folder in the documents library just fine.
New occurrence: Powerpoint presentation sent to to one of our executives that he wanted to share with the others. He copied it to a shared folder that is mapped to the exec group by policy. Now, VPOps can see it, VPAtty can see it, CEO cannot see it when accessing it through the same drive mapping.
So now I have found that this is not exclusive to document libraries, and not folders.
It has presented itself on different client computers each time.
It is not exclusive to files and folders that have been "Dropped" into the folder from the server.