Probably something with a router at a major trunk or something. I've had all kinds of weird things happen. Once I could not get any websites that started with the letters A thru J.
I suspect that most of the flood of SPAM and virus programs we get are substantially more than just over ambitious marketing and retarded cretins with too much time on their hands. Since the USA is the largest internet using group in the world, some of these actions are more than likely direct electronic attacks by terrorist groups.
I mean, let's face it. Look at the contortions they will go through in order to get those messages past the email filters. Surely no one in their right mind actually trying to sell viagra is going to believe that if they can actually defeat all of your SPAM blocks, that their getting the message through will finally land a sale for them.
So I believe that there are also automatic shutdowns in place at major junctions on the internet that will shut down completely when the junk traffic attacks warrants it. This is generally done via IP address blocks, so it is not to be unexpected that many legit sites would get blocked as well every once in a while.
I had a severe problem a while back because the IP address of my server evidently had been used by a major spammer before I got that server. I had a devil of a time clearing that one up.
Now the odd thing, in the case of this thread, is that both FaunaClassifieds.com and CornSnakes.com are on the same server. Different IP addresses, but the same box. It is unusual, but not impossible, that one would still be running and not the other unless I just happened to be doing something on that particular IP address.