http://wiki.guildwars2.com/wiki/Dierdre's_Steps
Dierdre’s Steps is a hidden area in the Mount Maelstrom zone. When you enter this area, it’s extremely likely to encounter a game crash. As soon as I took the portal to enter the area, my game crashed. Subsequent attempts to login just resulted in instant crashes, meaning my character was stuck there.
Occasionally, about a third of the time, I’m able to access the zone without crashing instantly. However, merely walking around the zone can occasionally cause crashes as well.
I have no idea what causes this and why I’m sometimes able to explore the area and sometimes I just crash.