That's a toughie because it could be your video or your monitor; though my guess is its your monitor. I would suggest plugging another monitor into it and seeing if you have the same issues - not always the easiest thing to do if you don't have one available to you. Another option would be to download the latest drivers for your video card, look for drivers for your monitor if you can find them (can be difficult for older monitors). So many possibilities... Does your monitor menu have a "degauss" option? Could be electrical interference and a degauss would help that. Is your monitor getting hot? Check the vents around it and clean them out with a can of air, leaf blower, or air compresser if they're dirty. If the cable has any kinks I guess it could be causing the problem but I've never personally seen it happen... I would be concerned with it being a fire hazard if there is any obvious damage to the cord. Be sure to keep the screen turned off and unplugged if it's damaged and you are not in the room with it. I guess that's a start for ya.
I've seen two monitors go weird and then go out similarly. One I had to degauss a couple times a day, it would get all purpley and after a week or so it just wouldn't turn on. My old 21" Raster Ops acted alot like yours. It turned out that it was a misalignment or something, the red green and blue weren't lined up and it was cheaper to replace it than to repair it. It gave it a fuzzy kind of effect. It was old but it was my big baby and hard to part with.
Hopefully some others will have some more experience in the matter. These issues can be tricksy