When you say you don't use either I assume you mean you've turned them off?
If so then your next step is a master reset to see if that cures it.
Apps>Trip Planner>Trip>Go>Select Next Destination>Start
If a great number (more than 29) of intermediate (intersection) via points are embedded in the route gpx file from BaseCamp or another App, the Nuvi55 may create additional contiguous Trips upon import in order to touch all intersections.
To my knowledge, the Nuvi 55 doesn't have those features. If it does, they're not listed anywhere in the settings I can see. I've made no changes in the settings on the gps or Basecamp. It worked flawlessy before yesterday. Today, I attempted to run the same route, same gps. It took me a completely different way. At times, the highlighted route showed straight ahead while the voice + turn indicator told me to turn. Another time, it showed + told me to travel 4.6 miles + turn rt on SR93. Half way there it changed it's mind + told me to turn left on some county road. In panic mode now, I'm leading a big three day ride to WVA tomorrow. If this thing doesn't follow my routes I'm screwed. Don't know if it's the gps or Basecamp.