[CentOS] CentOS 5.8, xen kernel, and nfs4

G'day,

I have a workstation running CentOS 5.8 with
kernel 2.6.18-308.el5.  This workstation needs
to mount a NFS4 directory on a server (mysvr in the
example below).  If the computer is running the XEN
kernel (uname -a reports ...2.6.18-308.el5xen),
my NFS4 share is mounted but "ls" reports an error.

Xen kernel:

   uname -a
      ...2.6.18-308.el5xen

   mount | grep mysvr
     mysvr:/ on /mnt/mysvr type nfs4 (rw,nodev,hard,intr,addr=1.2.3.4)

   ls /mnt/mysvr/data
     ls:  /mnt/mysvr/data:  Not a directory

When I boot to a non-xen kernel, the mount works
fine (and has for a few years).

   uname -a
      ...2.6.18-308.el5

   mount | grep mysvr
     mysvr:/ on /mnt/mysvr type nfs4 (rw,nodev,hard,intr,addr=1.2.3.4)

   ls /mnt/mysvr/data
     myfile.txt
     ...

Any ideas on how I can fix this or should I go back to NFS3
on my server?

Thanks,
--
Wade Hampton