I am currently experiencing a problem when adding file attachments to nodes in Drupal 6. When attaching a file and clicking the upload button, the screen goes white. I checked the files directory and the file does not appear there so it would seem it never gets uploaded. This problem occurs on the production server but not the test server. I have tried displaying php errors by modifying the index.php file but that does not display anything. I have the php memory set to 154MB but still no dice. I have Googled and searched this site but can't find a solution. Has anyone else experienced this problem? Can anyone provide some insight as to what the cause of this might be (and hopefully how to fix it)?
Ubuntu 10.4, Apache, PHP 5.3, MySQL 5.1
Drupal 6.22, CKK 6.x-2.9, jQuery UI 6.x-1.5, jQuery Update 6.x-2.0-alpha1, plus a whole boatload of other modules (that may or may not be relevant).
Thanks for any possible insight into this.