Planes get "stuck" and refuse to fly

[fsclips]

Hi

I have come across a very strange bug.

One of my long haul planes simply stopped flying after landing at my home base. The aircraft status went grey ("on ground") and the plane has been sitting there for several days.
I have tried to de-activate and activate the route, change it to a different aircraft and then back to the original one, but nothing works. The aircraft status remains grey and the plane just won't fly anymore.

Now a short haul plane has started to do exactly the same.

Has anyone else had this problem?

Many thanks.

Stefan