As you can see on the lower right the localization strings don't seem to have loaded or placed and the same with the minimap (minimap worked properly in game). The minimap is a small rainbow image that says "img!", a place holder I assume.
This was in a random match, like many bugs it has appeared a few times but doesn't seem to have a specific cause.
Have you submitted a support ticket with the screenshot, and if possible a DXDiag after it happens?
Support tickets tend to get looked at sooner - can't recall if this is an already know issue so it never hurts to report, worst that can happen is they say we are looking into it.