The "Show Explanation" freezes page

I would like to add the explanation feature to the questions when someone answers them to explain why it was correct or incorrect. But the 'show explanation' freezes up my screen and doesn't seem to display correctly either. Not in IE and not in FireFox.

The page get's a dark grey filter and I can only refresh the page to get it to start over.

Hello Saskia,
Please open a ticket and share your backend & FTP login credentials here www.wdmtech.com/support-tickets , We'll look into it.