After nearly 2 days without any issues at all, the "Likes" problem started again just now. (~7:35 AM CDT)
In the hopes of troubleshooting / diagnosing, I ran CCleaner, cleared my cache, etc. When I re-loaded PF (my bookmark is directly to the "New Posts" search), I got the style sheet problem again on top of the "likes" problem (images below). I was not having this problem before I got the "Likes" problem.
So.... I clicked through a few posts hoping the problems would clear.... No luck. Then I clicked the "Settings" link and the style sheet problem was resolved. Clicking "New Posts" again brought up a correctly formatted page. Likes are working again as well.
I went back and ran CCleaner again and the pages & likes are still formatting / working correctly.
So.... Is there maybe something about clicking "settings" that loads some browser setting that affects how the site is formatted in a browser?
Or, was it just a timing thing... that while I was trying to chase down some clues, whatever the problem was corrected itself and had nothing to do with clicking on settings?
That's all I can think of at the moment.