A few months ago, my screen began shaking slightly, and has been worsening every since, to the point that it hurts my eyes now to use the computer. Here are the facts:
* My computer is an iMac about five years old. Other than the screen, it runs pretty smoothly.
* The screen began to shake when I had the computer in my dorm room at school. It continues to shake now that I have it at home.
* I read that screen-shaking is sometimes caused by magnetic fields. I've tried turning off electrical devices like fans and lamps, and removing them from the room, but I'm not exactly sure what things have magnetic fields, though, and how big those fields are, so I could be doing it wrong. I also tried putting a metal cookie sheet around the computer to protect it, but I only have one sheet and it didn't seem to work no matter where I put it.
* A couple of times over the past few months the computer screen has suddenly and completely stopped shaking. This lasts for about an hour or so. Then, rapidly, the screen begins shaking again, until it reaches the same, eye-wrenching level it was at before.
Anyway, I hope you can help. I'm happy to try any suggestions, short of "Buy a new computer."