After you login to your Drupal site you immediately see the message "you are not authorized to access this page" or "Access Denied: you are not authorized to access this page"
You can't even access the admin menus. You get this error with the Drupal admin account (i.e. the Drupal main account) or any other Drupal user account.
When you upload an image using the built-in Drupal upload image or even the CCK imagefield feature you receive and error message that looks like raw html.
This problem does not appear consistently some node work some do not. This intermittent problem seems random but is consistent on a given page.
Symptoms: When you try to access your template admin pages within Drupal (/admin/themes) you get a blank page.
Under "administer » logs" you might see the error:
call_user_func(Copy of phptemplate_templates): First argument is expected to be a valid callback in E:\DomZeus\wwwroot\modules\system.module on line 572.
You just upgraded to php 5.2.0. You can login to your Drupal site but as soon
as you click a link, like "administer", you are logged out and receive the message:
You are not authorized to access this page."
The following solution is verified on Drupal 4.7.4 please adjust to your version of Drupal. The solution consist of adding a few lines of code in one file and removing a few lines of code in another. Remember to make a backup copy of these files before you make the 2 following modifications.