Make your cone do this.

The cone on the right is exactly the same, I just lowered it until the upper edge of the base of the cone just barely pokes through the ground, which will eliminate the problem you are having.

Of course, having the cone do this, you usally need to re-position the angle and placement to get the light ray to be kinda where you want it again, but this is a neccessary evil.

Contact Me | Gallery | Freestuff | IMDB Credits | Personal Site
"I want to be what I was when I wanted to be what I am now"