@ Mike Somers. On your 500 GB unit you will have the virtual disk 2 package installed. Network shares are mounted on the remote HDR as USB drives, and this package makes the share accessible by pressing the blue button (storage) on the remote. That is why you see a screen pop up with the options you mentioned: the HDR thinks a physical USB device had been plugged in just after start-up. You can just dismiss this screen with the exit button. It used to bug me, so I uninstalled virtual disk 2 and now leave a USB pen drive plugged in: as this device is present on booting you usually don't see this screen.
Foxlink is meant for a simple, one-way link of two units. Does Foxlink set the mount point as the '/media' share? If it does, and you have this set up on both machines you will get a recursive share situation which will lock up your units. For a two-way link, uninstall Foxlink, install the network shares automount and nfs-utils packages on each and set up NFS shares (you could alternatively set up Samba shares, but unless you also want to share attached USB drives, stick to NFS). On each unit (for access to video content) set up 'My Video' as the mount point (folder=_mnt_hd2_My Video). Don't mount the media folder directly on both units as you will create a recursive share.
Edit: I've added a screenshot. Simply create a folder in '/[Modsettings]/NFS' with the share name you want, open this folder and edit the 'folder=' (as above and in the picture) and 'host=' fields, the latter should be the IP address of the remote machine (use underscores rather than dots as in the picture).
Admins: the previous poster should probably have created a new thread in the custom firmware section. It doesn't bother me too much but not doing so might irritate those of an anally retentive disposition.