This particular problem is due to open_basedir restrictions on your server. To fix, open ultimatebb.php, and find:
Code
	if (!$fx) {
		$location = figurelocation();
and change figurelocation(); to figurelocation(1);

I reported this a couple of months ago, so it will probably be fixed in 6.7.3.

Charles Capps
Former UBB.classic Maintainer