I don't use an actual bookmark, just what pops up when I start to type secure. I'm here often enough it is the first on my list. Note, I am using Chrome because the "Internet" application that came with the OS is awful.
That would explain why the secure messageboard link works: there is no right-hand inline frame on that page.
I've found that once I've gotten to the messageboard web page, it is relatively easy to get back over to the Paizo home page from there.
I've been having the same issue lately. Have to refresh the page ten or twelve times to get it to load correctly.
I'd assume that the problem is indeed with the right-hand frame, as it only ever appears once I finally get the site to fully load.
This is a frustrating experience.
I also use Chrome and I've been having the same issue with it loading through it for a long time, but I believe I figured out a (maybe temporary) fix:
Open the menu (three dots) and click on the i with a circle around it (or just to the left of the address itself, click the sheet of paper). It'll prompt site setting, which you click on to clear it. This will allow any redirects to open normally.
I hope this helps the other Chrome users out!