I'm one of those weird people who read entire archives of comics from the beginning. Now, somewhere between May 16th, 1999 and May 19th, 1999, the next button stops working. Manually changing the link either does nothing or brings me to the newest comic, so I'm quite frankly stuck where I am.
May 16 and 18 do the same thing. May 19th loads today's comic...
Not only does it annoy archive readers, it breaks Comic Rocket too.
Edit: Actually all of the 1999 E3 (May 12-18) strips show the wrong comic and/or have the next button broken. The first comic after E3 (http://www.penny-arcade.com/comic/1999/05/25) displays today's comic just like the non-existent 1999/05/19 comic.