We have had similar problems with our 7000; the problem is intermittent; I sometimes can solve it by rapid (or rabid) pressing of various orange buttons on the control, which usually will get it working. We have also had it stick in the active mode, and can only break out by throwing the breaker.
My sense was that the contacts under the orange keys may be corroded; the SeaTalk bus could also be at fault.
Considering the age of the unit (16 years), and it's worthiness on a long voyage, we are replacing with Raymarine EV-400 and multifunction display (which can communicate your desired course with the auto helm). Total purchase price $3,550 US. Peace of mind, priceless.
Rock Hall, MD