I have the same problem alsoToday I had strange facebook behavior, too.
Klicked "Like", but nothing was published on my facebook page. Another time I klicked "Like", it showed up on my facebook page but wasn't counted on my forum page.
A third time I clicked "Like" and there a layer popped up in which I was asked to fill in a comment. Wenn I clicked in the form, it disappeared.
After some testing I honestly think that it seems to be a facebook problem.