I don't believe the notification email is the problem. I can reproduce it in other ways. If I go to User CP it'll display the control panel and then auto load the main page. The only way I can get to the Use CP is to very very quickly click on one of the links. It'll load the main page, then load the User CP.
I just tested it and it happens with both IE and Firefox.
Can you try going to your User CP and see if you can get to it? That's probably the easiest test. Try this URL and you'll see what I mean. http://www.smokingmeatforums.com/forums/usercp.php