I wouldn't recommend to use a 14m in light wind to learn how to kite. In 15-17 knots your GF should be using a smaller size kite (i.e. 10m if around roughly 60-75kg). a 14m kite should be only for heavier dudes (110-120 kg+) or for light winds with an experienced rider. You'll save her lots of frustrations by simply avoiding to go out in anything below 15 knots... this will help her to built more confidence.

Other than that, make sure your kite is properly inflated (8psi for Catalyst), and that your 4 lines have an equal length (line tuning). Also it is much more likely the kite will drop on slack lines when you keep it a 12'Oclock, which most beginners do.

Generaly the wind is not 15 to 17 Knots its more like 12 to 13 Knots she was not out yesterday i just thought i would have a crack on her kite for a change.
I am in broome and we always have light wind so we ride larger kites. the kite is basicly brand new so i think it would be a safe assumption that the line lengths would be correct ? but i will check them to be sure.
You are right it does only do it when the kite is sitting at twelve

Would shortening the rear lines make the kite sit further back in the window? i will have a look this afternoon and see if there is any adjustment at the bar end, there is no option to change to a shorter knot at the kite.

User error is the most likely cause here. Get her to stop flying it forward at the top of the window at full speed.