Heroes 6 - Discussion

My graphics card seems to be glitching out quite a bit. There are these black lines running across the screen. If I ignore it, the game freezes. If I minimize and then maximize the game, it temporarily fixes the issue. However, I have to wait a long time for the "resources to load..." Plus, there are some strange glitches appearing in the inventory and other menus. And eventually, the game crashed with a fatal error. It all seems a bit suspicious. I've played for so long, and suddenly this happens. Maybe it's just certain maps that cause these glitches, or maybe I'm missing something...