Godaddy happened to call me, so I tested my web pages.
Surprisingly, they did not work! Instead, I saw this most unexpected Apache default installation page:
"It Worked! The Apache Web Server is installed on this Web Site!
"If you can see this page, then the people who own this
domain have just installed the Apache Web server software
successfully. They now have to add content to this directory
and replace this placeholder page, or else point the server
at their real content.
"If you are seeing this page instead of the site you expected,
please contact the administrator of the site involved. (Try
sending mail to <Webmaster@domain> Although this site is
running the Apache software it almost certainly has no other
connection to the Apache Group, so please do not send mail
about this site or its contents to the Apache authors. If you
do, your message will be ignored."
Unfortunately, I am the admin for my site! And I don't recall upgrading!
I really dislike it when things like this happen. It's always hard to track down.
Most confusingly, the above file didn't even exist in my htdocs. Nor am I running v2.2 - I'm using v2.0! Nothing seemed to have changed. Weird.
In my case, the problem was a momentary brownout over the weekend that reset my router. This caused my ISP to give me a new IP address, which failed to update at my dynamic DNS provider (dyndns.org). So my "dynamic" addresses were pointing to somebody else's box!
Moral: If your websites suddenly screw up, check your dynamic DNS settings FIRST.