Hmmm, in fact I'm fairly certain the problem lay in navigation, not rerouting.

Tested further, and now didn't even get to the blue box, saying recalculate. When I enter the data I want to route to, I see the route, now hitting 'start navigation', gets me into the same "freeze", i.e. the car position is updated, until it runs of the map, as it's not autocentered after touching the screen. But then modrana doesn't react to keypresses.

It's not really freezing the system, as the CPU load doesn't rise, modrana can be closed, but it's dead to input.

Left it like that for a couple of minutes, in hopes it'd pick up, but didn't. Before, the blue box also didn'h display right away, but in the end it did, but not now. Same problem a couple of times, so it's a recurring behavior.