emacs server quit working

[address@hidden]

My emacs has been running for about 10 days and suddenly the server
isn't working any more:

% emacsclient --eval t
emacsclient: connect: Connection refused
emacsclient: No socket or alternate editor.  Please use:

        --socket-name
        --server-file      (or environment variable EMACS_SERVER_FILE)
        --alternate-editor (or environment variable ALTERNATE_EDITOR)

I tried running server-start in emacs and it returns nil and I still
get the above.

If I run a separate emacs it starts a server and clients connect to
the new emacs.

What happened?