Grayed-out Security Screen

I installed iThemes Security, but when I click “Security” from my WP dashboard, the screen loads, but then gray striped lines appear across the entire screen and I can’t click anything. I’ve tried deactivating all my other plugins, to make sure it wasn’t a conflict. I still get the grey-striped screen. Any thoughts on how to resolve this?

https://wordpress.org/plugins/better-wp-security/