I would be more concerned about the vibration than the magnetic field. The magnet isn't strong enough to do anything unless it comes REALLY close to the H/D. I have heard tall tales about refrigerator magnets on your case causing problems. That's BS. The magnet has to be VERY strong and be VERY close to the drive to do damage. We aren't talking about a cassette tape here.
Change the world. Of one person. Today.
If your equation requires either a complex combination of variables to get the desired result OR you can't seem to get the result regardless of the variables....it ain't your variables, it's your constant.