The reason behind this bug for me remains unclear. It doesn't seem to be my hardware problem since I can run all other games on my laptop at high graphics without going black screen.
It started happening earlier today while I was doing Crucible of Eternity. It just suddenly goes black screen. All I was running in the background are Google Chrome for music, and Discord for contacts. I tried tuning the graphics settings to lowest, but it continued to randomly black out in the middle of gameplay. It doesn't seem to have a pattern. Even when my game is idle, it blacks out. In the middle of a loading screen? Black out. Applies to middle of fights and middle of chatting as well. The black outs generally occurs from 2~28 minutes after I started up the game. The game seems to be still running regardless, and I can still hear ambient noise, the mouse button is also the Guild Wars styled whenever I'm on the game window as well. But no controls seems to work. I can't press anything nor do anything. I tried setting it there for a few minutes, but it continued on to remain blacked out. Hopefully someone with technical knowledge can help me with it as soon as possible since it has been severely disrupting my farming efficiencies this whole time.