Thank you for your reply!
I see the PG whether I’m logged in or not. I usually work from a Xubuntu Linux machine with Firefox browser. I tried accessing the blog (still not logged in) from a WinXP machine with Firefox, and got precisely the same thing. Then I tried Googe Chrome on the WinXP machine, and still got the letters ‘PG’, but it was inside a box in the upper-left-hand corner. In the middle of the box is what looks almost like a broken-picture icon, except that it’s green.