Running SLES11sp2 and running Datasync as a XEN virtual machine.

I upgraded the Novell Datasync application on the VM and this went thru fine
and the system update and is working correctly.
but .....
on a reboot of the virtual machine generates the following error:

waiting for device /dev/xvda to appear: ok
invalid root filesystem
exiting to /bin/sh

I then type "exit" and then everything works 100%

The "mount" command returns "/dev/xvda1 /boot" and "/dev/xvda3 /" which all
looks correct.

Any ideas ......