>Suddenly one day, in the middle of a presentation using the projector, the system screen shrunk, apparently to a REAL 1024x768 (versus the interpolated (I assume) display of previously which filled the full screen).
>This 'real' 1024x768 only occupies about 5/8ths of the screen.

This happened to me with one of our Compaq laptops. Never could fix it, but a reinstall of WindowsXP brought everything back to normal.

What I do to avoid this problem now is to go into the display settings and scretch the desktop onto the 2nd montior (the projector).