Particles

So what's happening is that the particles are billboards, and they're rotating to face the camera.  I sadly do not have my project handy at the moment where I am, but you want to set the view they face so it doesn't do that wonkiness you're talking about.  It's really simple, if you look at the renderer of the particle system, there's a thing there you want to change. 

Sorry for the vagueness, literally going on the memory of what it is as this is something I had to do about a month ago.  Seriously though, very simple once you change that one thing, will probably fix your issue.