I was doing the Serpent's Ire meta event, so there were a lot of people around but no more than usual for a big event and I had no noticeable lag or other issues. Close to the end I was south of the main group attacking a branded crystal, so the two bosses and the majority of players were off-screen behind me, but the crystals waves of purple attacks were on screen and I was kiting around it. Just as I killed it there was a bright flash of purple then my screen went black.
At first I thought the event had finished and maybe there was a cut scene or something (I've not done it often and not for a while, I don't know if there is or not), those can take a few seconds to load for me so I didn't think anything of it until the 'No signal' message came up on my screen and it went into power saving mode, meaning it had lost it's connection with the PC. I could still hear the music and ambient sound from GW2 coming from the speakers but nothing else and nothing I tried - wiggling the mouse, alt+tab, ctrl+alt+del etc. worked to get the screen back on. I had to restart the computer to get it back on.
The PC restarted fine and apart from missing the final reward for the event it doesn't appear to have had any impact on the game, but I'm not sure what could have happened and I'm concerned it might be a problem with my PC. Has anyone else experienced anything like that, and do you know if it's a problem with the game or possibly something on my end?