Seems to be a circulation issue. There is a disorder like that. Does your hand get clammy too?

Nerve damage.

Go to a doctor and get an ergonomic set-up... or... don't use the computer so much.

In my case I think it's mostly this:

you're more or less inactive when you are working on the computer, I've heard your body can actually go into sleeping-mode or something close to it. your body heat is in part generated by your muscles, which are most of them inactive when you work behind the computer. Also blood flow is low. All of this basically means your body cools down. If your whole body cools down your body takes action, digestion, shaking (moving muscles), etc. But since your hands and feet are most 'outer' looking from your torso, they will cool down quickest, and especially with the low bloodflow, far sooner than the body cools down so much that it takes action.