same for me, happened twice now, once in the silverwastes while using an arrow card and the second time while using the tailoring station in LA.
win 10
i5 3350P
AMD Radeon HD 7800 2 Gb VRAM
16 GB RAM
If i close the game via ingame exit to desktop, the game becomes unresponsive, if i then open the taskmanager i can see my desktop, but cannot interact with anything on it with my mouse except for the task bar, as GW2 doesn’t seem to minimize, but just becomes invisible. However i could run cmd.exe with “win+R” and kill the process that way.