Why? What happens when you test?
Please be more precise. I already showed you that nbc.com and www.nbc.com
are different addresses but since www.nbc.com is the only one which is an alias
for an akamai server I suspect it is www.nbc.com which is giving you your
problem symptom. Furthermore, especially when you are having problems connecting,
you should be trying *only* full URL, e.g. server name with protocol prefix.
So, the only thing that is worth discussing is what you see when you try the following,
either by using it as a link or by copying it in your Address bar:
None of what you have listed as having tried addresses those points.
If you can't prove that you have connectivity to a particular server and port
(e.g. using telnet 80 or a different browser) anything you do using the hypothesis
that something about your browser is causing your symptom could be a waste of time.