There's a little mini-updater for the DOS and Windows clients in case the console encounters an old version in the middle of a task (for instance, in a fixed Ghost Boot Partition). The file in the console install directory
UPDATE.EXE is a self-extracting zipfile that contains just the minimum DOS and Windows client files.
If the console thinks that the clients are the wrong version, it sends this first (after this, for Windows it will then try sending the Client.MSI full installer) and runs it. For some reason it seems to be that the file has gone missing.
What version of GSS do you have installed on the server?