Try going to the lexmark website and downloading the latest drivers for your printer. They usually come as a self-contained installer so you don't have to worry about picking the correct one out of a list.
EDIT: I was trying to locate a direct link for your driver, but there is no '3100' printer on the lexmark site. Is there a letter preceding the number?
Edited by twardnw, 10 April 2007 - 05:16 PM.