That's the one I've experienced problems with. A couple of weeks back it would not load at all. Then all that appeared was an IIS7 welcome box, which I did not want to explore. Now the front end appears, but clicking on Advanced Puzzles I get the following:
"500 - Internal server error.
There is a problem with the resource you are looking for, and it cannot be displayed."
This appeared also when I tried the Contacts page.
I begin to wonder if the site has been taken over, by fair means or foul.