I got the same problem. I can run the game with most settings on high and it runs very smooth. The problem is that I get this screenfreezes with the background sounds that turn into a annoying buzzing sound. From that moment I can’t do anything at all. Some times I’m able to alt tab and close the game by usig ctr alt delete. But then it its still somehow running and have to shut down my pc. Other times I just have to hold my power button because the game crashed that badly. I tried diffferent solutions posted on the internet and I can state to confirm that none of them will be a solution. I hope NCsoft and Arenanet will fix this asap(this week). I mean this are bugs which keep ten thousands of people from playing. Better fix this issue before you start fixing regular bugs and other updates.
cheers Onyxhammer