Documenting this here now that the next Nvidia driver is out. In case it stops happening which I hope it does. But since the driver Nvidia released on 23 of December 2014 (347.09) I have had GW2 completely randomly stop responding or crash, sometimes.
This seems to on occasion be preceded by seemingly normal operation of the client but with glitched audio (ie. no sound effects of any kind play, just stuck playing a background music track indefinitely) when the client is closed under these circumstances the process stops responding.
Alternatively, sometimes odd graphical artifacts can be seen on screen or the UI or other elements of the game may begin to flicker. When this happens the client is already in a non-responsive state, however, on occasion Alt-Tabbing to desktop may help to recover from this (assuming this can be done, which is not always the case).
There may be two separate issues with similar symptoms here, hard to say for certain, the problems with the audio as well as the non-responsive state with glitched visuals may in fact not be related at all but in either case these problems are recent.
In both cases the only way to regain normal operation of the PC is to terminate the process from task manager with twist. In this unresponsive state GW2 still prevents all mouse input from going through to anything on the desktop (even if nothing besides an iconized GW2 may be seen on task bar anymore) including an active Task Manager window (the cursor can be moved but it retains the in-game graphic). I used keyboard navigation to set the Task Manager window to be always on top and at that point it accepts mouse input again thus allowing the non-responsive process to be terminated.
I wish I could say there is a more discernible pattern to these issues, however, all I can say is that sometimes high player density and lot of skill effects can make it more likely but not in any way guaranteed.
OS: Win 8.1 64bit
GPU: Nvidia GeForce GTX 675MX