Graphics issue
I have some strange flashing happen from time to time, but have put it down to my ATI drivers 12.8.
They are not perfect drivers but the best set I have found for GW2. With higher drivers I get some mad flashing, something along the lines of what you are experiencing.
My drivers are the latest nvidia drivers the 306 ones. This only started yesterday so im not sure why its doing this.
It isn’t the drivers, happens occasionally with NVidia as well regardless of the advanced beta drivers loaded. Its a game bug what needs fixing and such.
Found a fix. If anyone has this issue with nvidia card, it is because the ambient occlusion setting is glitching the game up. SO go into your panel and turn it off for gw2. Cheers.