Found a new problem when your in edit mode with the edit entities tools.
Coordinate fields. You start with this.
Then you start to edit the field, and the coordinate field is made empty by accident or purpose.
And you decide not to change it, pressing outside the tools window or TAB. the field coodinate returns to zero, instead of the old coordinates that where present before.
So the result is that your entities is running away ! (yes i never put a leash on )
If the focus of the edit field is lost and the field is empty, place the orginal coordinates back.