@Usagi_T, I flew the same error. Try before solving the puzzle to close all other pages of the site, must be treated properly. Ie, close all pages grandgames, except the one where the link to the puzzle, and just go to the link (do not open in a new tab!). Not very convenient, of course, but what to do(
by the Way, you have chrome? Interestingly, this is everywhere or a separate feature of chrome)