imagettfbbox returning screwy values

I'm having this really bizarre problem with imagettfbbox. The values it is returning seem to be way off the scale. I have gd and ttf support compiled into php, (running on latest stable apache 1, gentoo linux, latest stable php) When I call imagettfbbox I get very very large numbers back. They don't seem to make any sense at all. Here's my code: <?php $txtSize = imagettfbbox ( 30 , 0 , "/usr/X11R6/lib/X11/fonts/truetype/georgia.ttf" , "test" ) ; print_r ( $txtSize ) ; ?> And here's the output: Array ( [0] => 1076630208 [1] => 137911840 [2] => -1073777096 [3] => 1073930763 [4] => 1076630224 [5] => 1076625940 [6] => -1073777064 [7] => 1075882071 ) Has anyone seen something like this before? Suggestions? It's not a dodgy font. Switching fonts makes the numbers change but only slightly. For reference, my phpinfo is here: http://www.sympages.com/info.php Help! Thanks, Simon