Problem with Windows Live Messenger (MSN)

In the last couple of days my home network has suddenly been plagued with a problem with MSN messenger, and the hotmail website.

All of my computers are able to connect to any website i ask it to with the exception of hotmail.com. Usually receive a message along the lines of:

via Mozilla

and the messenger just simply refuses to connect, aside for intermittently every once in a long long time. Usually coming up with the standard unable to connect error message that shows when there is no connection.

Thus far i have investigated a virus theory, and all the computers have come up clean, switched out my router(wireless), restored factory settings on the router, and reinstalled the browser/tried other browsers as well as msn messenger.

What im stuck with right now is wondering if the internet provider blocked a port that Microsoft uses for the software as well as the website, or my router is being externally manipulated.

Edit: the only odd thing about the entire situation is that i pulled out a laptop that i usually only use at school, connected it to the network -> and msn/hotmail works perfectly fine on it.confused

any ideas would be greatfully welcomed
thanks