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.
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.
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:"