checkout_shipping --- blank page!

I'm getting a blank page (white-page ) when I get to the checkout_process level of the purchasing process.. where can be the error here?
...mystore/index.php?main_page=checkout_shipping

My store contains two languages English and Arabic with the English version it was OK, with the Arabic version I couldn't go through out the whole process as I got the blank page.. I tried everything to fix that by replacing the Arabic folder for the modules from the Language directory with the English one but that didn't help! any help please ?
by the way I set the debug file to help me to find out where the problem is and I got this report :

[23-Aug-2009 03:27:42] PHP Warning: Cannot modify header information - headers already sent by (output started at /home1/arabbro1/public_html/champ/includes/languages/arabic/modules/shipping/freeshipper.php:28) in /home1/arabbro1/public_html/champ/includes/functions/functions_general.php on line 44