.Xauthority invalid after random amount of time

[Vincent Kersten]

Dear people,

In my network we share /home/ via nfs.
Since (i think) the arrival of nfs v4 (combined with a new version of
ssh we frequently suffer from the problem that the .Xauthority file
becomes unusable after a 'random' period of time.
This can be from 2 days to 2 weeks
I've been googling far and wide, some people seem to have a simular or
same problem, but a solution is nowhere posted
the error goes like:

    X lib: connection to "local host:23.0"refused by server
    X lib: Invalid MIT-MAGIC-COOKIE-1 key

the only solution is to log out, move the .Xauthority file and then log
in again

ssh options have

    ForwardX11 yes
    ForwardX11Trusted yes

and the clients nfs avoid the nfs v4 caching.

Any Clues?

It almost seems to appear random; one thing i read it might be about
different clients trying to access / lock the .Xauthority file in the
same time.

I hope you can help me out on this one.

Thanks,

  Vincent