I just grabbed a hp scanjet 7400c that was at the office , and I'm trying to hook it up to my home computer. I found the driver, installed it, followed the directions, and when I run the hp precisionscan pro program that it installs, it never recognizes the scanner. It says "Sorry, scanner could not be initalized. (Scanner not found.) The weird thing is it was working at the office, and it seems like it should be in working order...what to do?