Yesterday I was onsite doing computer work with a customer while sitting at a metal [stainless] table. Whenever the computer [my laptop] was on the table, my mouse pad was so glitchy that it was useless - the cursor didn't respond to most finger movements. We eliminated all potential sources of electrical noise but with no effect. If I lifted my computer off the table, the mouse operated properly. I tried sitting the computer on a piece of thick cardboard but even that didn't fix the problem. I'm guessing this was somehow due to the damping of magnetic fields, but that is hard to believe.