Possibly 2 separate bugs here. Firstly, when in windowed mode, if you minimise and then restore, everything on the map (except for the floor and the glowing bits round the tops of towers) would disappear for about 2 seconds every 3 or 4 seconds, then reappear etc. This seems to be a windowed mode bug only, minimising in full screen and restoring seems to work ok.

Also since first experiencing this minimising bug, my screen now flickers at all the menu screens (even after DG restart etc) except the stardock/GPG and intro movie (this happens in windowed and fullscreen). In game the buildings/players/grunts no longer disappear, but the bottom character bar, the map and the top menu bar all flicker pretty much constantly. This wasn't happening before when the buildings disappeared. The only thing i can think of that might have caused the initial flicker (and made me minimise) was that my avast anti-virus just finished updating. Also, if i'm in windowed mode, and then minimise/restore, the ingame flickering of characterbar etc disappears, but the disappearing bug returns...

EDIT: First one is still a bug, second was a problem with my graphics card I think.