[Wed May 30 17:47:56 2012] [error] [client 10.11.22.202] Directory index forbidden by Options directive: /var/www/dokuwiki.hayley-group.local/data/
This suggests that someone is trying to directly access your data directory. It should be protected by an .htaccess file that forbids access to that directory altogether.
[Tue Jun 12 11:21:46 2012] [error] [client 10.11.22.202] PHP Warning: call_user_func_array() expects parameter 1 to be a valid callback, class 'Doku_Renderer_xhtml' does not have a method 'rowspan' in /var/www/dokuwiki.hayley-group.local/inc/parserutils.php on line 664, referer:
http://dokuwiki.hayley-group.local/doku.php
Not sure how this is happening. What version of dokuwiki are you using?
[Tue Jun 19 10:00:07 2012] [error] [client 10.11.1.214] File does not exist: /var/www/dokuwiki.hayley-group.local/doku.phpdata
This is very strange, since it indicates a corrupt filename is being requested: doku.phpdata. It could occur is someone accidentally entered that name in the url. But dokuwiki is set up so that you do not make a direct call to doku.php.
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And what Operating system is DW installed on? And if Ubuntu or Debian, how was it installed?