Perhaps someone has your two passwords and they are changing it to their own. Not sure why though as they obviously are not using your account for board spam or anything. Try using a totally new password (non-family related) instead of recycling the older ones. If someone is toying with you, they can continue to do so as long as you continue to recycle old passwords they already know.

It's unlikely, but a fresh password never hurts.

With great power comes Awesome irresponsibility.