A very common error while trying to modify the user profile in Drupal 5.x is:
warning: Cannot add header information - headers already sent
This is usually an issue associated with line breaks or text file encoding.
Confirmed Solution for Drupal 5.1
Stop using MS Notepad, Download Context ( http://www.context.cx/ )
Make sure all your files are in DOS (ANSI) not Unicode. (Context -> Convert Test To -> Dos)
Usually the files that are in Unicode are the ones that display in the error message.
/includes/theme.inc
/includes/common.inc
theme-dir/template.php
theme-dir/user_profile.tpl.php
Eliminate all but 1 line break from the end of all of the php (template and user_profile) and inc (/includes/*) files.
Please only post specific solutions to your problem as comments.
