To get this to work, the one in the header I had to modify [/skins/elf_zen/_contact_msg.form.php] as there were two error messages than read
Notice: Undefined variable: samedomain_htsrv_url in /home/calstock/public_html/skins/elf_zen/_contact_msg.form.php on line 35 and on line 65

Line 35
was: $submit_url = $samedomain_htsrv_url.'message_send.php';
now: $submit_url = '/htsrv/message_send.php';

Line 65
was: . . . ($redirect_to, $samedomain_htsrv_url) );
now: . . . ($redirect_to, '/htsrv') );

/plugins/_calendar.plugin.php

Since version 6.7.8 have to move lines 806 too 834 the footer section to below the body section to get rid of validation error see http://forums.b2evolution.net/calendar-plugin-1