Error “tinyMCEPreInit.start not a function” in FF3, firebug. WordPress 2.6.2, fresh install, on php 4.4.8.
My problem was a known bug with PHP’s realpath() (bugs.php.net/bug.php?id=34552), called in wp-includes/js/tinymce/tiny_mce_config.php:20.
Realpath will output a null string if any ancestor directory of the file is not readable — so folks running out of home directories – this is likely your case.
My fix – change tiny_mce_config.php:17
function getFileContents($path) {
// if ( function_exists('realpath') )
// $path = realpath($path);
$path = dirname(__FILE__) . "/" . $path;
(please forgive multiple postings)