crash in standalone but not in editor - appears to be caused by UI

I have a project that runs without errors in the editor but crashes when compiled to standalone.

The issue appears to be caused by enabling and disabling GUI components.

I get the following error in the player.log

 Receiving unhandled NULL exception
 Obtained 12 stack frames.
 

but no stack info is included in the log (is it saved somewhere else?)

I cannot consistently reproduce the problem in a test project but I can make the problem go away in my project by removing the commands to enable and disable the GUI objects.

Is this a known issue or does anyone know where I can look to investigate what is going on?

I'm building for OSX