[r7648] several crashes

[whoami]

I just received the third crash in a row with r7648 (Windows nightly; with Pak64.German). The circumstances are not completely the same, but there seems to be a relation to the editing of schedules. Without user action, the game runs nicely in fast-forward mode.
I will investigate further, but this patch-level appears unsuitable for use. My last tried and known good one was r7640.
EDIT: with a default map, a single vehicle and very little user action, I have received five crashes in a row, normally with the line schedule open. But I cannot say yet how to reproduce the problem.

[Dwachs]

this was introduced precisely with r7648 :( 

Edit: should be fixed in r7649