User blog comment:DaNASCAT/Technical Update: March 7, 2016/@comment-13301-20160309082920/@comment-11733175-20160309102924

I hit a similar problem yesterday. I appeared to be logged out, served an advert in the top of the page (which was a huge surprise as I use adblock) and my JS console was more full of errors than usual (adblock normally causes a dozen plus due to the sheer number of external resources loaded for ads). I also noticed site CSS (and probably JS) failing to load, leaving severely broken navboxes and infoboxes. User CSS/JS was broken as well as preferences, but as I was logged out I didn't think too much of it at the time.

A couple of minutes later it was fixed by a simple refresh, preventing me from investigating further.