Anyway... THE ISSUE:
I couldn't post a comment or "Like" anything on Facebook because every time I click on those buttons/links to do so, it takes me to this address: http://www.facebook.com/ajax/ufi/modify.php that contains just a white page.
Fortunately, it seems to only happen on Firefox. Unfortunately, a lot of what I do on Facebook I like doing with Firefox. (FB doesn't work well with Opera, while FB-ing in Chrome is fast, but I miss some functionalities I use with Firefox, while with my Safari browsing in general feels "cumbersome").
Simply change http: to https:
simply becomes https://www.facebook.com/
(Go on, try the links. Click and see some difference :'p)
Then, say "Yay!" ='D
I've read that for some people, it happens with the other popular web browsers (Internet Explorer, Opera, Chrome, and Safari). Hopefully, this is the same fix.
Easy peasy ='p