I'll consider my hand slapped, and try not to meddle with your setup in future!
Although, as I use Kubuntu on my laptop, and I haven't found anywhere to create an NFS mount? I know I could use Samba on both systems, but, it just seems a little odd to use an extra interface, where *nix systems have a very good system for seamlessly mounting drives across the network?! (Hence the /export/home entry in fstab) I assume your advice will be go the Samba route?!
I'll probably try as suggested, remove the mount point(s) from fstab.
If I reboot in single user mode, I should be able to unpack my original tar file which contained the base home drive directory structure (no data!), if all else fails, a complete rebuild over the weekend at some point, once I've made sure I've got things duplicated!
Thanks for your help and scoldings!!