Define pages are not written to the database, they are written to files in the includes/languages/YOUR_LANGUAGE/html_includes/YOUR_TEMPLATE/define_xxx.php files if the file exists in YOUR_TEMPLATE otherwise it writes to the html_includes directory. This writing is performed by the define_pages_editor.php file located in your admin directory and references file locations identified in your admin/includes/configure.php file... If the installation was done in accordance with iinstruction such as http://www.zen-cart.com/entry.php?3-...d-of-upgrading then the includes/configure.php and admin/includes/configure.php files should both be pointing to the correct base folder structure and editing the file(s) following the above structure.Further, when the define_main_page.php is selected for edit, the line above the text box area should provide the complete folder/file path for the file being edited... If that file path matches your expected location, then perhaps the file has access permissions set on it that prevent editing.As to the discussion of logs, the error logs in a default install of ZC 1.5.4 are directed to the logs directory off of the root of the store and are also identified in the above two configure.php files. Perhaps posting those to files (obscuring admin directory and db credentials) will shed some light on the issue if the above doesn't help.Please when posting identify what actions were attempted, what reviews were performed and the success/failure of each... This will help those helping you and possibly someone that ends up having the same issue.