That reminds me of a particularly humorous episode Star Trek Voyager where the ship's doctor (who is a computer program projecting a hologram of a middle-aged man with an extremely conceited personality) tries to prove that diseases aren't as bad as humans claim they are by modifying his own code to give himself a simulation of a cold. The "cold" is designed to end after a few days like a real cold would but one of of the crewmembers surreptitiously extends the expiration date while he isn't looking, which drives him into a state of panic when he doesn't understand what's happening to him.