My company set up a site for a client a few years ago with Concrete5 CMS. Since then we downsized and web designer has moved on. Client has been happily updating site but has now started getting issues with diary page display. My freelance designer went to back-up/copy the site but was met with 'page not found' in system and settings. Our hosting company spotted an error in the code and reported as follows:

have only been able to find an error with the concrete file code
HP Fatal error: require_once() [<a href='function.require'>function.require</a>]: Failed opening required 'Zend/Uri/Http.php' (include_path='.:/usr/lib64/php:/usr/lib/php:/usr/share/pear') in /home8/trevorpi/public_html/updates/concrete5.5.2.1/concrete/libraries/3rdparty/Zend/Http/Client/Adapter/Proxy.php on line 27
It looks like it is an error with some code on a 3rd party addon. The web developer should be able to either fix the code or disable the offending program to allow the rest of the site to work
You can find that in the "Error Log" icon in the "Logs" section of the control Panel
My designer can see the error but can't get to the code to fix it. Any ideas....getting desperate now...