'You don't have permission to access this site...'
That's what my browser (IE 8) says.
Who is forbidding me to access any site?
Is it possibly the owner of the site?
Yes, you guessed it.
And, if so, how can he single me out?
Because your IP address does not fall within a range or list of IP
addresses permitted to view the content.
Let me guess: you were trying to access a site across an international
border, say as someone in Europe tries to access a media streaming content
service in the United States (like Hulu). This is because the offered
content is targeted to certain users.
If you tried access a company or corporate site, perhaps you accessed an
internal host meant only for corporate members.
Don't take it personally. If you were to go to business establishment to
be a customer of its services, and some security official (bouncer?) or
other employee barred you from entering, instead of feeling angry and
disrespected, just tell the person, "I was going to see if I would be a
customer of your services, but clearly you want me to take my business
elsewhere, so I will." Saying that really does make you feel better.