More Simulator

[kiv@vftronic.no]

When running multiple trains in the simulator, after some time a random track is coloured yellow, but there are no train present in the fields, this situation will block all other traffic in this area of the layout.
By move the mouse pointer across the train field (red frame in the image), a hided train appears (See image 2), but train is not active.
Any tip what my be wrong?