I need to give you a bit more information, and it's very interesting.
I just discovered that with the Wysija Plugin re-activated, I DO GET the email notifications.
But with every prior test, as I re-activated each plugin one by one, and tested the form in between, I did NOT receive email notifications.
So, I only get the email notifications of a contact form when the Wysija Plugin is active. But then I also get the error screen (http://screencast.com/t/qD9G06ZXawj) upon submitting the form.
Make sense?