Password Hacked

While I was going throgh some files on my pc I was surprised to find a MSN Messenger chat history folder in my documents that goes to my baby sister; "something's rotten in the state of Denmark"  I said to myself, she has access to my account somehow maybe she hacked my password through that silly hint I had...

Anyway I was thinking wether to snoop in on some of her chats or not. I believe in people's privacy but didn't she invade my privacy when she entered my account? So after much thought I decided to do it having in mind my two sisters' record of using the internet; giving your home phone number to a total stranger that you met in a chat room, stupid!! so I found she's chatting to older guys, much older guys, she's 14 and they're over 20 to say the least, but what I found was innocent so I just changed my password and made the hint say: "Never think of stealing my password again"

After I put more thought into the whole thing I changed back the password to what it was and decided to keep watch a couple of more weeks, if things remain normal then i'll change my password and just tell her that it's not cool if she ever tried to steal my password again, never to mention finding the chat history; but if I found that somethings were wrong I'll think what to do then.

I'm feeling guilty hacking her privacy but you can't be too careful these days, not on the internet anyway.