That is the troll cave. Do you already have the quest to deal with the trolls? If not, get it in the farmlands, just across the bridge, before entering or you might miss out on a bit of experience.
As for the crashing, there is a cut scene conversation when you get close enough to the troll king. Try running the configuration program and temporarily switching to software mode, and perhaps lower the resolution; this helps with some cut scene problems.
