This happened to me twice yesterday. What occurred was quite strange, the sound in guild wars 2 cut out and was replaced by some kind of whining siren rhythmically increasing and then decreasing in intensity, the second time it occurred GW2 crashed and I had to end GW2's process to stop the noise. At first I thought it was skype but I think the culprit has something to do with too many sounds at once as the 2 times it occurred involved over 50 people all AoEing, the first being with the Shatterer and the second being in WvW. My only guess is the game can't handle it or something, I have all settings in GW2 on max including sound settings and it isn't my hardware that is at fault as it's more than enough for GW2 and has not caused troubles elsewhere.
Not really a major issue, just requires me to close the game but I'm curious if this has occurred with anyone else?