Game crashed when I start sprinting

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Hi, I had this problem since I started playing the game in January. Sometime when I enter a dungeon, nothing happen at first but if i start sprinting, the game crashed. It happen once every 2 days so i was ignoring it until last month, where it happen at least once every day. I sent a ticket to the support and after 5-6 round of tunning, fixing and testing, they gave up on me saying something like they are out of solutions and I should look elsewhere for help. Now the issue have gotten worse and it dced me 50% of the time when I enter a dungeon, including 6v6 (it happen in both walk in or in f8). I tried to search through google and bns forum but found no issue similar to mine. Is anyone have an idea of what is going on with me? I have Window 7 and GeForce GTX 960