Only reason is you are using AMD GPU and drivers really sucks. But luckly there is a very simple fix for this.
How To Fix It:
- Open "Heroes of Newerth" folder and open "game" (/Heroes of Newerth/game/).
- Create a new empty file named as "startup.cfg".
- Open startup.cfg with a text editor and type this to inside: SetSave gl_modesetting "nvctrl,randr11"
- Save, exit and play your game. :-)