Guild Wars 2

Here are my specs: (I have two comps exact same build, but only one has the issues.)

Model: ASUS Desktop PC CM6850 Series
Proscessor: Intel Core i7-2600 CPU @ 3.40GHz
RAM: 8.00 GB
System type: 64-bit Windows 7
Graphics Card: Geforce GTX 550 Ti (Currently running version 306.23)
Display: TERRA 6222W (Resolution: 1680 × 1050, Refresh 60Hz, Color 32-bit)

Not sure if there is anything else I need to list, but I hope this will help in finding whats wrong. Also both computers are only 2 months old.

I can go up to 20-40min. from when i turn on my computer to play, before I get the first screen flicker. The screen will go black for about 2-5sec. Sometimes it will show my desktop in that brief moment before going back into the game. The sound sometimes cuts out or will still play. After the first time it happens, it will then happen every 2-5min. Every 3rd to 5th time it will stay either black screen or go to my desktop but my mouse will still have the GW2 skin. I’m able to just alt+tab to then see the error box that states that GW2 had a graphics error that it couldn’t recover from and had to close.

This started around the 10th of this month. (Not sure on exact date sorry.)
I have made sure that Windows is up-to-date.
I have downgraded the graphics drivers to several different patches.
I’ve played with the 3D settings and in-game settings.
Since I don’t know how to mess with clocking I’ve yet tried that, mostly cause I don’t want to screw up.

This is the only game that has the problem. I also play: (With no issues)
Aion
Diablo 3
Dungeons & Dragons Online
Elder Scrolls V: Skyrim
Fable 3
Mass Effect 1-3
Rift
Star Craft 2
Star Wars: The Old Republic
World of Warcraft