You really haven't been hijacked, the page you set as your homepage is your personal MSN page and you have to be signed into your MSN account to go there. You are being redirected because the cookie that allows the site to see you are logged in is a non-persistent cookie (I believe). This means it only allows you to be recognized during the IE session you signed into and disappears when you close out IE.
Many sites do this for own protection so others may not access your account. You can make the situation a little easier by putting a mark in the box which saves your e-mail address and password on your computer, then you will not have type your information all the time but you will still have to click the sign in button when you first start IE each time.
The down side to doing that is that anyone else who uses your computer will be able to get into your MSN homepage. A word of advice to you though is do not save that information on anyone elses computer, only on your own.
There is no justice, there is just us.