The cruise ship computer constantly monitors the heading of the ship vs. the programmed path the captain or other has entered. If a feedback problem occurs in the ships monitoring of the direction of the ships servo's it could become disorented and acutally drive the controls of the ships props into extreme positioning causing an incident until someone shuts her down. An of course the faster she's movin the worse the incident. I believe this is what happened.
The autopilots on modern cruise ships are much more sophisticated than that. The ship's officers usually enter a destination (latitude and longitude) and either a desired time of arrival or a desired speed of travel. When engaged, the autopilot continuously computes and sets the course and speed from the ship's current position, obtained from an inertial navigation system (INS) that's updated automatically by the global positioning system (GPS), to the destination via the most direct ("great circle") route. The autopilot also has settings for details like the maximum rudder that it's allowed to apply to maintain the desired course. If there are islands or other obstacles along the route, the officers also can specify intermediate waypoints to take the ship around those obstacles.
Of course, the deck officers on watch can take manual control at any time and typically do so to avoid other vessels that may cross the ship's intended path. When they restart the autopilot, it automatically adjusts course and speed to accommodate whatever deviation the avoidance of other shipping, etc., may have required.