Flame Thrower Particles Tutorial Problem

I am trying to duplicate the Blender Guru tut on building a flame thrower. Very early into the exercise, I get a strange behavior (when I press Alt+A in the 3D View). It starts happening as soon as I set the particle damping factor to 1.0. Here is a look at frame 26. I tried to upload the blend; never tried this before; it failed; maybe too big? I am running 2.58.1 on Win7 (having used 2.57, 2.56, and 2.49 on the same system, I have seen almost no problems of any kind in the past). Anybody know what is causing this?