I know this is old-ish now, but I guess I found the problem. RadeonPro was causing it. It started appearing in a lot more games since I installed a second GPU for Crossfire (And I'm pretty sure CFX meant CrossFireX). I just got rid of RadeonPro and everything works fine now.
I guess this topic can be locked?

Bump?
Anyone else experiencing this too? It's kinda annoying as I have no clue what I did wrong.

It's good to know (I think?) I'm not the only one with this problem, I couldn't find anything about it (by searching with google). But I browsed through the tech support forum, and couldn't find anything about it either (I opened every topic which I thought it could be, so I didn't open topic's like "Leaderboard problem" as it (probably) has nothing to do with this).

Some "CFX" thing is blocking my screen.

It's not game breaking but it's rather annoying, I'd like to get rid of it.

Also, is it possible to change my resolution in the level editor? I don't see an option for it, and it always launches in 1280x720 for me, my native resolution is 1920x1080. I've added -1920x1080 as launch option, but it doesn't change anything.