Problem with Inventor Sketches not Having any Constraints

Have you run into a problem in Inventor where your Sketches have no Constraints? I.e. ends of lines are not joined to each other.

Well this can happen if the Inventor Sketch Constraints have been turned off. To check this, whilst in a Sketch, with nothing selected, right click in an empty space. Select Constraint Options from the right click menu. The dialogue below will be displayed, check that all Constraints are ticked on, if not click Select All and you should be back to normal.