I dont use Media Network.
I use a library on a networked machine.
Every thing i do on the office machine is using the library through the network
I shuddered when I read that, and as I know it is what you want to do, I didn't respond. If you happen at any time to have the HTPC and your Workstation running MC, sharing the same library on a shared network location, you will have two applications reading from and writing to the library files, at the same time. Those files aren't designed to be shared that way. They aren't multi-user. They are just normal Windows files. All sorts of strange things could happen to the files, and in MC. File corruption, lost file. MC rebuilds it, and all of a sudden MC doesn't work the way it used to, or has lost data.
Then you get this sort of thing happening.
DLNA is enabled.
I think I have just realized what it was.
I just reinstalled a backup from the HTPC and now the zone is showing.
I think when I was doing backups in the office it was backing up without the zone.
One other thing. If a backup is restored from the office it will loose all current settings from the HTPc so I guess it is safer to use a backup done from the HTPC problem is how to tell which are which as all the auto ones have the same name.
The answer to that is to never restore an automatic backup, and regularly perform manual backups on the HTPC, named so that you know what they are.
But with your setup you are always playing stuff via DLNA, from the HTPC to your Workstation is DLNA. From the Workstation to the HTPC is DLNA. Well, probably, because you can't turn on DLNA without turning on Media Network in MC. So maybe your setup is using the MC Media Network, and you just didn't realise it. Media Network is better than DLNA anyway. Also, if you are using DLNA, at least MC controlling MC via DLNA is likely to work best.
Really, what you should be doing it putting your library on he HTPC, setting up your Workstation to use Media Network for general use, like playing stuff, or even tagging files. Then when you need to do real maintenance like renaming and moving files in MC from your Workstation, use
Teamviewer or one of the VNC tools, or just Windows Remote Desktop as I do.