nfs issue after client crash

Wed Nov 8 18:45:59 UTC 2006

I have a bunch of Ubuntu clients which mount /home at boot time from a
FreeBSD 6.1 NFS server.

When a client crashes it won't mount /home at boot.
In that case, trying to mount manually gives "can not read super bloc".

The client still appears in the "showmount"output of the server.

Sometimes /home will be mounted after the second reboot but sometimes
not even after several reboots (I haven't been able to find a regular 
pattern here).
If I restart the NFS server or just wait long enough (e.g. one day) 
everything is OK.

Is this a server or a client issue?
Is this related to the client still showing up in showmount?
Is there a better workaround than restarting the NFS server?

Regards,
Thierry.