Guild Wars 2

I seem to have the exact same problems as you Godin! IT all started for me a couple of days ago with my graphics driver crashing every 10 minutes or so while playing, i thought litte of this at the time but the it escalated to my entire computer becoming unresponsive, the last screen perfectly preserved as you explained. I can still hear the audio playing. Im quite bummed since i upgraded my PC for this game.
My graphics drivers are the latest nVidia beta drivers (306.02).

I’ve tried the following:
Rolling back to older nVidia drivers(304.79)
Re-Installing the entire game.
Underclocking my graphics card by 20-30% (Allowed me to play for a bit longer, but still ended in a crash)
Lowering the graphics ingame to the lowest possible (performance)
Forcing my fan to run at 100%

My specs are as follows:

EVGA gtx 550ti
8 GB ram (corsair vengence brand)
intel i5-3450s
ASrock z77 pro-m motherboard
I am running 64-bit Windows7 Ultimate.

My computer never created any dump files or any arenanet crash logs, so im unable to post those.