Thank you, The option has been disabled
It is a pair of courier servers configured to for virtual mail box mounted on /var/vmail
It is happening on both of them, which leads me to think it is a NSF issue
192.168.100.XXX:/share/mail /var/vmail nfs rw,async,nfsvers=3,wsize=32768,rsize=32768 0 0
192.168.100.XXX:/share/data /var/data nfs rw,async,nfsvers=3,wsize=32768,rsize=32768 0 0
Side note , since the upgrade the server performance has increased considerably!
once I chmod -x /usr/bin/du that is .. Thank you for your response .