Anytime my wife or myself play on her PC, while running around our characters will be randomly thrown into the sky and out into the ocean to die. Sometimes it just gets stuck in the air, in which case it screams a lot and then the game disconnects with a spam error. It is extremely frustrating and basically makes the game unplayable, because sometimes it will happen before we can even get the character back to where it was before it happens again.
This also happens in buildings and caves, in which case it simply throws the character into the wall and kills it instantly. At least in this case, you go to the nearest wayshrine, whereas ending up in the ocean usually puts the character on the other side of the map.
This does not happen on my PC, which has nearly the same specs but is running Windows 7, whereas hers is Windows XP. I have also seen others complain about this issue, but have never seen a solution. Is this a known issue, and is there a way to fix it?