black outs

[enkeli]

I am running my world, and it will black out on the rendering for 1-6 seconds at a time. There are no error messages associated with this, and the program keeps on running fine in the background during the black outs (I can hear the sound files being played etc). What could be causing the black outs and what can I do to stop them? I have 8 avatars in the world along with "gaze" lines. The lines are updated every tenth of a second to show where they are looking. (Using math.tan in the calculation of where they are looking). It blacks out even when I'm not moving around in the world, just watching from a stationary point.