I remember watching this movie when I was little but I can't remember what its called. The semi-trucks in the movie drive by themselves and I remember seeing a green glowing light in the sky. Ring any bells to anyone? This is driving me nuts!

Sounds like this one could be the 1986 opus Maximum Overdrive (http://www.imdb.com/title/tt0091499/), directed and written by Stephen King and starring Emilio Estevez, old-timer Pat Hingle, and Yeardley Smith of The Simpsons fame.