The glitch seems to be only with Firefox. It does not happen in Explorer or Safari but for some reason extra pages are added when using Firefox and they end up blank when you select them. This is an example from Firefox of the 3rd page of a 2 page thread.
If this is what I think it is, then it's not browser related, but my guess is that you're signed in on firefox, and not signed in with the other browsers. Try it signed in and out and see if it makes a difference.
As for scrolling down on posts with many images, just press the "End" key on your keyboard.
Also, can you link me to the topic with the whimpsy pager please?