Only try this if...
1) You have a good set of video card drivers and can play every game but guildwars normally without crashing.
2) Make sure its not a overheating problem many people think it is, usally not the problem.
3) Tried everything else people have told you and yet still crashes you.
Ok i definatly figured out why my system crash was happening to me maybe this will help you if you have tried everything but your guildwars still freezes an u cant alt tab or cntrl alt delete.
TURN OFF your VENTRILO OR TEAM SPEAK ....
My ventrilo was crashing my guildwars when people were joining the server i closed vent and played all night free from crashing i know many people use vent or TS to voice chat with guildies but it definatly stoped me from crashing. hope this helps.
Does Your Guildwars Crash? README
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