I get this black flicker on the bottom half of my screen when the in game time is day mode. It only seems to happen when I'm on the ground and more frequently when I'm near objects. It doesn't affect the radar or message window at all, and it doesn't happen during night time (game time, again). I noticed that turning the shadows off makes the flicker go away.
I'm have a 64 MB Nvidia video card with 768 MB of memory and run Linux with the latest NVidia driver. Not the latest and greatest, but nothing to sneeze at. I would think that my computer should be able to handle bzflag without any major graphical hiccups.
Does anyone know what might be causing the flicker?