This one is not always "do this" to solve.

For example, what happens if you use the Google DNS on this laptop?

And given all the malware out there and site blocking those antivirus suites have, I rarely guess if it's that. Sorry but the list gets too long today.

Let's start with the Google DNS which is noted at a link to follow.
Bob

-> http://www.youtube.com/watch?v=2_ufVAHgw20