Alysandra,
I have a friend who has had the same problem, also with them being immediatly located by a different account, different IP address, going so far as using a "friends" account, they made their sim Private, even closed their sim and opened a new one. No matter what was done the stalker seemed to find them.... and several times my friend was located within a 15 minute time span. This person was even stalked into their real life, Yahoo, MSN, and managed to aquire personal informaton. This has gotten to be a real bad situation. I have managed to get them to look at filing a stalker