WP 'Pages' not found

I am trying to get the blogs directory, members directory, site search and global tags operational with WP 3.1 multisite using the WPMU Triden child theme (have installed both parent and child themes as per instructions) in the Site admin custom home page. After activating the plugins to be on the safe site I create pages called 'blogs', 'members', 'site-search' and 'tags' all of which appear on the menu bar as expected. 'post-indexer.php' and 'glocal-site-search.php' are located in wp-content/plugins as per instructions. The permissions are such that the Apache group www has write permission (ie 775). However, clicking on any of the WP pages invokes the error:

Sorry, we can't find the content you're looking for at this URL. Please try selecting a menu item from above or to the side of this message to get where you'd like to go.

The strange thing is that this does not generate a 404 error in the associated Apache error log.
Moreover, other user generated pages that I create manually do not open either. This same behaviour is apparent when I switch to the WPMU-Nelo theme. I am really not sure whether this is a theme problem are something else. Other users on the system using different themes are able to display pages they have created. I have taken a look at the database and tables 'wp_site_posts' and 'wp_term counts' are both present and populated.