ViewSonic VA550 problem with horizontal blurryness (by 2 users)

I was given a VA550 for free. Cool huh, until I started having problems about 2 months ago. When I first hooked it up I had no problems, but recently, after the computer is turned off for any amount of time, the screen is distorted with horizontal fuzzy lines. When I use the buttons on the front of the monitor, the screen that pops up has no fuzzyness at all, but any info running to the screen from the tower has the fuzzy problem. After it warms up for a time, most of the lines clear up. I tried changing the refresh rate from 65 to 70, and that helps occasionally, but today it had no affect. After leaving the monitor and computer on for about 4 hours, it looks perfect. Any ideas?