particle problems

i''m using the snowstorm particle systems code from the book "opengl game programming." however, when i port it to my own program, something strange happens. particles fall in straight vertical strips of approximately 8-10 particles with little or no spacing. this makes it appear as if a long line is falling. i can''t seem to figure out what is wrong since the only parameters i changed were the origin, height, width, and depth. the original code from the book can be downloaded at this site: http://www.primagamedev.com/tech/downloads/76153330/ch15.zip any help will be appreciated, thanks.