Automounting NFS share via fstab fails on raspberry pi.

[switch10]

I am accessing the same NFS share on both a 64 and 32 bit arch system without any issues. My Raspberry Pi however fails to mount the share on bootup. I can mount the share manually, but it randomly unmounts itself even when the share is not being accessed.

I have xbmc installed as well, and it starts up at boot. Xbmc mounts (I assume) and accesses the NFS share without any issues, but I have no idea where it mounts the share. I've checked /run/mnt/, /mnt/, and /media but I can't seem to find it. So I've disabled the xbmc service temporarily to trouble shoot the issue. The NFS share still won't mount when the Pi boots. I'm still able to manually mount the share, but again, it unmounts itself randomly....

I have nfs-utils installed on the Pi, along with all of the required services started, and enabled at boot (nfsd.service rpc-idmapd.service rpc-mountd.service rpcbind.service rpc-gssd.service)

systemctl --failed returns:
$this->bbcode_second_pass_code('', 'media-nas.mount loaded failed failed /media/nas')

I've tried several different fstab entries, here is my latest one:
$this->bbcode_second_pass_code('', '192.168.1.106:/mnt/md0/Users/dave/ /media/nas/ nfs defaults,_netdev 0 0')

I'm using the ethernet port on my Pi, so I'm pretty sure the randomly unmounting is not due to network instablility.

Any ideas whats going on here would be very much appreciated...

Thanks,
Dave