Apple has determined that all Apple File Services connections to the server are terminated if a client tries to open or get info on a file that has a filename longer than 31 characters.
All connected clients receive the message, "The file server's connection has unexpectedly closed down." Clients connected over TCP disconnect immediately, while connections over AppleTalk timeout after two minutes. Once disconnected, clients can immediately reconnect to the server.
Until a solution to this condition is reached, you should avoid sharing files with names longer than 31 characters with Apple File Services.
Mac OS clients are not able to create filenames longer than 31 characters. However, they can be created at the Mac OS X Server computer or copied over from other file services running on the server.