Perhaps your parents have used Parental Controls to lock you out?
Sorry, just had to go, though I probably shouldn't have.
Either your firewall is locking you out of IE7 (most likely) or your User
Account Control (UAC) is doing it. In your firewall you may have to add IE7
as allowable.
You can turn UAC off by going to START/CONTROL PANEL/USER ACCOUNTS to find
out which is doing it. You will see "Turn User Account Control on or off"
at the bottom of the "Make changes to your user account" list.