OK, some news :
with the service menu enabled, you get a two things :
- You get a "remove all options" button next to the "add option" button.
- The WinNT files are not anymore read-only
- you access the service menus described in the service manuals[\li]
I removed( renamed) the "options.ini" file in the hope it would be rebuilt to some defaults, but it didnt't happen. But the "erase all options" did exactly that.
Now, options are maintained between reboots
The option menu allows you to set the exact model (ZVR, ZVC, etc) and some other options (installed attenuators).
For example, ZVR is menu code 1.0.0.3
It works instantly, the INFO showing a ZVR model, but for some reason this was lost between reboots and the VNA was still restarting as a ZVRE
Strangely, after I left the VNA switched OFF for 15 minutes or so, it restarted as a ZVR.

The bad thing is that I'm afraid I've lost one of the detector calibration files (including the backup) while exploring the menus the first time I opened the service menu.
But this is another story...
I've ordered a CF card and an adapter, but it's a bit late...