Internet Explorer 8 doesn't load pages opened in new Windows, but does in same window and tabs.
Windows 7, reinstalled Internet Explorer 8, and updated.
Optionally if you want another program to open a new window (say you click a link from within outlook) you can check "A new window" under "Open links from other programs in:"
Did you try to reset IE settings? You can do this from, IE Options->Advanced Tab->Reset.
Keep in mind that, doing this will disable all 3rd party add-ons and reset your settings.