Sometimes I can't like anything, although sometimes--but not always--reloading the page helps. Other times I get ARG4 or ARG6 and still other times when I click the like button turns to unlike, but I don't see that I've like the post. I suspect the latter phenomena occurs mostly when I'm trying to be the first one to like a post.

I don't understand the inconsistency. It's been going on for a very long time, and I sometimes suspect more in certain fora such as Hyatt but not so much in DL.