@Ashley: I can't add an action. When I try to add an action in the event sheet, the focus goes off the main window as if the 'add event' window is open, but nothing appears. I have to hit ESC, which I'm assuming closes the invisible 'add event' window. I've managed, by randomly hitting Tab and Enter, to get some events to appear, so it's obviously open, but its invisible and I can't interact with it in any way.
I have a notion what might be happening - I opened Construct 2 when I was using a dual-monitor setup, so its possible the event window is opening in that now non-existent space. How are the initial coordinates of the event window done?