You probably have a guitar with single coil pickups. I have this problem with my strat.

The only solution I know of is to move away from the computer. For me, I just have to be a couple of feet away from my laptop. I got a wireless mouse for my laptop to allow me to do this so I can navigate the website but be back a bit from the computer.

With my les paul with humbuckers, it isn't a problem.