If you don't want to block internet completely, then you can also setup a firewall on your computer/router to block all access from MSN messenger/IE. I think some firewalls also provide you with an option of supplying a password. So you can setup it to ask for password whenever MSN/IE try to access the internet. So when you want to access it, either enter the password or just disable the firewall. You can use spybot (its free) and has a firewall or anything else if you want. Hope this helps.