Can't access a website! What is a Gateway GEO-IP/BOTNET Alert?

This has never happened with me before. I was browsing a few websites using Safari, and decided to check a NGO website. When I first accessed it, everything was fine. For some reason, I accidentally closed the tab I had the website opened, and then tried to access it again. That’s when I got this message:

Gateway GEO-IP/BOTNET Alert

This request is blocked by the SonicWALL Gateway Geo IP Service. Country Name:United Kingdom Initiator IP:XXX.XX.XX.XX

I couldn’t figure out what was going on right away, and any website that says my access is being blocked and shows my IP up on the screen scares the **** out of me!

So I looked around the web and found this:

Geo-IP Filtering allows the administrator to block connections coming to or from a geographic location. Botnet Command & Control Filtering allows the administrator to block communications to suspected command and control IPs based on the reputation database built by the Sonic GRID research network.

So:

- If I first got to access the website without problems, then I don't believe my country is part of a geographic location they are trying to prevent access from.

- I'm really concerned my MacBook may be infected with some sort of virus and it's being considered dangerous by those Geo-IP/Botnet filtering services. Could my computer being used as part of a botnet without my knowledge?

Is there anyone in the community who can explain what’s really happening or tell me if my MB might have some sort of virus in it?

I'm so scared and paranoid! I have iAntiVirus installed and it has never caught anything. I have also used Karspersky for a while but deleted it after I ran out of the trial period. No virus or anything has ever been caught on my MacBook. I'm also afraid my computer might have been hacked? That'd be surprising to me considering that I have good internet surfing habits and never put myself at risk.

Please... can someone enlighten me about what's happening?