Thanks for the advice again Robin,
Yes, I think the camera has a problem. I made a backup of the settings onto an SD card, and then performed a factory reset (manually, using white balance switch) which worked, but still the only menu I can access is the limited 'User 1'.
I usually have my cameras serviced at Top Teks, so called, and they came up with the following suggestions to get into the engineering menu...
1. Holding the 'hold' and 'light' button in simultaneously then turning the 'menu' button on
2. Holding the 'reset' and 'light' button in simultaneously then turning the 'menu' button on
and also, trying to access the option menu holding the 'light' button on when pushing in the menu button.
Nothing worked, the omly menu I could access was the very limited 'User 1'.
They're putting in a call to Panasonic, but I'd imagine the camera will make its way to an engineering bench in the near future. Could be a corruption of the firmware or a board that needs replacing, hopefully nothing too serious. Apart from that, it's working beautifully!
All the best,
Mark