Hello
It looks like there is a maximum value set for the timer in the editor. I'll look into increasing this but in the meantime you can add the 'Script' optional property to the page and paste this code into it:
Code:
$('#x_pageTimer').remove();
x_currentPageXML.setAttribute('timer', 2400);
x_addCountdownTimer();
This overrides the value you have set in the editor. I'll admit that I haven't waited until the end of 40 mins to check the message appears at the end of the timer but it looks like it should all work correctly
Fay