The only three things i can think to recommend to you is.
Go here
http://support.amd.com/us/psearch/Pa...ds=&items=2 0
1.)Download the most recent driver and catalyst control center.
Un-Install your current driver. Do this by going to control panel, Find the driver package in add/remove programs. Usually named "AMD vision control center", "Catalysis Control Center", or "AMD/ATI display adapter"... Select express uninstall all AMD software... Restart the computer and install the driver you just downloaded.
2.) Update your audio driver, this driver can also cause lockups... you will either have to go to your sound card manufacture site if your using one, your motherboard manufacture site if you custom built your pc, or your PC manufactured if you bought it from dell, gateway, ect ect.
3.) If one and two don't work, Run guild wars in XP compatibility mode. Do this by going to your gw.exe folder, right clicking on gw.exe go to properties -> then compatibility, and select WinXP service pack 2 compatibility.
If all this still fails you might want to test your memory is bad or if your video card is over heating.... You can use
http://www.memtest.org/ for a tool to test your memory ONLY IF YOU FEEL KNOWLEDGEABLE ENOUGH to do so... you can also monitor your GPUs temp using AMD Vision Control Center make sure its not ur GPU overheating. It could also be your PSU going out if your using a computer thats a few years old.... also if you have your computer plugged strait into the wall or in a cheap surge protector... micro surges in your house like the AC or fridge kicking on... even a vacuum cleaner can cause the power to drop low enough to mess up your computer processes causing it to lock up during power intensive processes....good luck, hope you find a solution