Guild Wars 2

Im creating this topic in order to find a solution to my prob if anyone has the same or just a good advice:)
Start the story quest ‘’a light in the dark’’ and when i get to the tomb keeper,after fighting him for a while my pc freezes/black screen and i have to force restart it.
Happened all 5 times i tried,at the same spot,and at that moment both my cpu and gpu temps where just fine(no overheating issues)

my spec
intel quad core 2.3
sapphire radeon 4870 512
4G Ram
W7

P.S. So far game runs smooth as hell with no probs at all

This belongs in the bug report section of the forum.