jpg support in php 5.3.3 with GD2

i have a weird issue on my Linode 512:

im running debian 5, w/ nginx, php5.3.3(with php-fpm)

phpinfo and gdinfo show jpeg support is ON.

when i try to crop (or anything else) a .jpg image, nothing happens.

if i try to crop a .png image, everything works fine.

Any ideas what can it be wrong?