Zumo 590 reboots when using Garmin OSM Maps

I’ve downloaded maps from http://garmin.openstreetmap.nl/ onto my Zumo 590.
As long as I’m just looking at the maps everything is fine. But often the Zumo reboots as well:

  1. When calculating a route
  2. When driving the route

Which is quite a nuisance when you’re on a motorcycle.

My neighbor uses the same device but from a different year and with a newer firmware version. He faces the same problem.
We’ve tried the Generic Routable as well as the Generic Routable (new style). Same issues.

Thanks for any suggestion on a root cause or a solution.