Hi paizo tech people.
It looks like there's a bunch of issues such as this one bouncing around at the moment, so this may well be on a list somewhere, but just in case...If I do the following:
1. Hover over the Pathfinder pulldown menu at the upper left of screen
2. Hover over the Rulebooks subcategory
3. Navigate to the First Edition Rulebooks item
4. Open that in a new window
Then it tries to load the following for a little while:
https://paizo.com/pathfinder/rules/first
But very quickly switches and instead displays:
https://paizo.com/pathfinder/rules
Cheers
Steve