This causes PSO2.exe to utilize 100% of the CPU when task manager isn't open. The below image shows PSO2.exe still running, but it's no longer in the task bar:

@coldreactive I've noticed the exact same thing but for me it only occurs when the game fails to load during a loading screen, the advert in the bottom left corner never appears and the loading screen is infinite until I F4 to bring up the exit game dialog, however saying yes does close the game but the .exe is still running.