Internet Explorer cannot display the webpage
 

I had just finished typing up an Announcement and clicked Save, only to get a "Internet Explorer cannot display the webpage" message.

Since this, I have not been able to get to the vB test site.
I get the htaccess challenge, but beyond that is the error message.

Also, at the same time, it would appear that I have the same error if I try to access the Drupal Admin page (forum access is fine).

I can still ftp to the server.

Should I suspect foul play?
Where should I look for code denying access like this?