Graphical error destroying game

Hello!
First off, I'm new to this forum, so a big HELLO to you guys.
Ok, here comes my problem:
I am playing GW for 2 days now and this bug occured to me very rarely in the beginning, but now that I am through with the beginning, I always get this error while playing the 3rd coop mission in Ascalon.
Everything starts quite harmlessly. I'm in the game, playing with my group and all out of the sudden the hair of my nec gets transparent. HP bars become white. Surfaces get transparent. This gets worse and worse and after about 20 seconds my whole screen turns to one blue or red square.
I can still steer my character (at least it SOUNDS like that), but blindly, I of course cannot play on.
As I have said before this bug occred to me earlier very rarely and so didn't really disturb me, but after I finished the beginning and especially in this coop mission, it happens again and again. I can hardly play longer than 5 mins in a piece.

Here are my system specifications:
Athlon 3800+
Geforce 6800 Ultra
1024 MB Ram
Windows XP Pro SP 2

I'm playing on 1280x1024, shadows on standard, no antial. everything else on high.
If you know a solution or have heard of this bug before, please tell me.


P.S.:
I have installed the newest drivers and directx.
I also know about the common Geforce error and have already changed the common driver.
I have even tried playing in window mode or in other resolutions: always the same.
In another forum I read I had to force vertical synch. on, but that didn't help either...

You more than likely have an overheating video card. Does this happen in any other video games? I have a GeForce 6800 Ultra and have no issues.

Here's a quick way to check if it's a heat issue. Open your PC's case and point a house fan to the inside (just for a test). Run GW and see if your problem resurfaces. If it does, we can look at other problems.

I just checked that with a quite powerful fan, but after 4 minutes and 30 seconds online, my graphics well... screwed up again, but still thanks for the idea.

After a few emails changed with a tech. support guy from GW, he finally gave in, that my PC is perfectly fit for the game. He told me they get tons of emails regarding issues about GF 6600 and 6800 Ultra.
He promised me that GW will fix that fast.
I personally, do believe him, because... I don't know, I have the feeling that the devs of this game somehow really care about their customers.... not like i.e. Lucasarts or Creative Assembly...

I guess this is on topic so anyways sometimes when i play mission I would see white rectangles on the terrian and some of my group members are white rectangles and I don't know whats up with that but except for the big white rectangles following me around, the graphics are fine.

Yea Guildwars is still a newborn game so it's bound to have some trouble.(Oh god my Netgear router [email protected] GuildWars with a burning passion) It is pretty rare to see what theyve done, where you make a direct connect with another person instead of playing directly on the server like on games like WoW and @narchy online.Don't worry man. Just wait for the next patch to come. untill then play halo with me or something.lol