Can't use the lower-right window

I'm about 60 turns into my first full game (I was starting to have hopes of unlocking). And something odd and disturbing has happened to the game...

In the lower right hand corner, there is an interface panel that has the faction shield, the turn # w/ an hourglass, a build icon and a recruit icon. You're supposed to click on these to pull up their respective functions. In my game, they have stopped responding to mouse-click.

I can double-click on a city in the campaign map to bring up the build/recruit screen and click on one tab or the other to flip back and forth. But no help for the interface panel in the lower-right. This is a big problem, as I cannot get to the faction interface screens, i cannot get to diplomacy & papal scolls and worst of all, I cannot end the turn.

It appears to be a corruption in the game-save file. Luckily, I have an auto-save relatively close in time, and if I load that, the problem disappears. I'm really more asking because I'm worried about it happening again and losing progress to that point.

Has anybody had this happen? What is to be done?