Paste the code here in the forum between backticks (the key to the left of the #1 with the ~ on it). WordPress will indeed strip some div code that is not allowed, but we cannot tell if we cannot see it.
2.1 version tinyMCE will replace <div> by <p> when saving post, you may change this by hacking file: wp-includes/js/tinymce/tiny_mce_config.php
about 24th line, find:
$valid_elements = ‘p/-div[*],-strong/-b[*],-em/-i[*],-font[*],-ul[*],-ol[*],-li[*],*[*]‘;