Starting this morning, with Google Chrome and IE11 at least, the StackExchange dropdown menu no longer works, except on the SE meta page. Instead, clicking "StackExchange" just goes to the SE front page.
Clicking to review a review queue (e.g. https://emacs.stackexchange.com/review/low-quality-posts) shows only an empty question.
Also, adding a comment just stopped working. I added some this morning, even after noticing problems #1 and #2, but now I can not add a comment, e.g., here: Search/replace-like feature for swapping text. The "Add comment" is not greyed-out, but when I click it the page just blinks - I get no text-edit box in which to enter the comment.
Google chrome automatically updated to 53.0.2785.116m, but I chose to revert to the previous style instead of the "Material" style (because the address-bar text was too small): top-chrome-md. Dunno whether this is related. I don't think so, because I didn't notice these problems yesterday, after the new Chrome version etc. I have tried closing the browser and clearing the cache, but that didn't help.
It's apparently not a Chrome problem. I see the same thing with IE11 - all the same symptoms: #1, #2, #3.