The Washington Post has an article about Dilbert cartoonist Scott Adams. He has focal hand dystonia, a loss of fine control in one or more fingers. This condition occurs frequently in musicians or others who rely on fine movements over many years. As you can imagine, this kind of neurological disorder can be a professional catastrophe.
Focal hand dystonia may represent an error in motor learning in which the extensive training of the finger motions causes a paradoxical blurring of the control regions in the cortex which are responsible for fine motions. Basically movements of the misbehaving finger somehow become "associated" with other intents, so that the finger moves when you don't want it to. One newish therapy tries to break the association by having musicians move their dystonic fingers while the rest of their hand is immobilized.
Adams is using a digitizing tablet to make his drawings at a much larger scale. In the interview, he says it's working for him because he doesn't have to push down so hard, and the larger scale means different hand motions (and probably different muscle sequences) are involved. So he is basically avoiding triggering the onset.
A nice technical reference to epidemiology and therapies is here.