Just wanted to share my finds when looking into this. I used a tool called Windows Focus Logger to try and find out the reason for the game to lose focus/alt-tabbing.What i found was that a process called " ShellExperienceHost " and also " SearchUI " made GW2 exe lose focus for a few seconds. SearchUI process can be disabled but ShellExperienceHost cannot be as far as i know as it is required to run windows. How to actually fix this problem i cannot solve, but this is the cause i found. Feel free to use the tool urselfs and see if you have the same results adminscope.com/downloads/window-focus-logger-gui/