Yes. As a matter of fact, after lots of testing, I found that the site loads via cURL on Firefox ONLY when I set the user-agent to NOT include the word "Firefox" in the user-agent string. So
curl_setopt($curl, CURLOPT_USERAGENT, 'blahanything Firefox blah');
does NOT work, but any user-agent string that does not have the string Firefox in it will work.
Very very strange. But the weirder thing is, I can visit yahoo.com using Firefox without cURL, which has the string Firefox in it.. obviously.
I am really just trying to get it so
curl_setopt($curl, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
works. And as of right now, using Firefox through cURL doesn't work.
P.S. on Chrome and Safari through cURL, I set the user-agent string to be a valid Firefox string and POOF, all of a sudden it doesn't work. So it definitely has to do with cURL + word "Firefox" in the user-agent string. Why?! I don't know!