$source = ereg_replace("<!--#toc_plugin#_TOC_OUTPUT-->", $display_content, $source);
$source = ereg_replace("<!--#toc_plugin#_START_CONFIGURATION-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_list_type=".$setting1."-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_start_level=".$setting2."-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_end_level=".$setting3."-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_header=".$setting4."-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_header_tag=".$setting5."-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_parent_tag=".$setting6."-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_parent_tag_id=".$setting7."-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_END_CONFIGURATION-->", "", $source);
$source = ereg_replace("<!--#toc_plugin#_START_TOC_INDEXING-->", " ", $source);
$source = ereg_replace("<!--#toc_plugin#_END_TOC_INDEXING-->", " ", $source);
should be
$source = str_replace("<!--#toc_plugin#_TOC_OUTPUT-->", $display_content, $source);
$source = str_replace("<!--#toc_plugin#_START_CONFIGURATION-->", "", $source);
$source = str_replace("<!--#toc_plugin#_list_type=".$setting1."-->", "", $source);
$source = str_replace("<!--#toc_plugin#_start_level=".$setting2."-->", "", $source);
$source = str_replace("<!--#toc_plugin#_end_level=".$setting3."-->", "", $source);
$source = str_replace("<!--#toc_plugin#_header=".$setting4."-->", "", $source);
$source = str_replace("<!--#toc_plugin#_header_tag=".$setting5."-->", "", $source);
$source = str_replace("<!--#toc_plugin#_parent_tag=".$setting6."-->", "", $source);
$source = str_replace("<!--#toc_plugin#_parent_tag_id=".$setting7."-->", "", $source);
$source = str_replace("<!--#toc_plugin#_END_CONFIGURATION-->", "", $source);
$source = str_replace("<!--#toc_plugin#_START_TOC_INDEXING-->", " ", $source);
$source = str_replace("<!--#toc_plugin#_END_TOC_INDEXING-->", " ", $source);