Problem with preview feature

I've never had this problem before, it started today, I think (I already had this problem after midnight).
I can't preview my posts before posting them on the forum. I click the "Preview" button and nothing happens :(
Does anyone has an idea what can be the cause of this?
Apparently only I have this problem.

test post

the preview function works for me

sorry, i can't help any other way.

OK, thanks, Wroclaw.
It must be something with my Firefox browser because when I log in using Google Chrome the "Preview" feature works.
I still don't know what happened to my Firefox, so if anyone has any ideas, I'd be grateful...

If you have installed any "add ons" to your browser in the last few days, try disabling them to see if it makes any difference.

I have Adblock Plus and I've already checked - the "Preview" feature works when I turn Adblock off (and then the ads show up ;/), but I've had it since, like, forever and I've never had such problems... Hmm, dunno...