This is a quick note to help you diagnose white pages or partially loaded pages.
White Pages
If you see a completely white page with no messages then this is most likely caused by running out of memory in PHP. Look at the php info tab of the Joomla system info from help menu in backend of your site. Search for "memory_limit" - if this is less than 16M the increase this to 24M (say).
You can do this via your php.ini, .htaccess or using this little plugin.
Partial Page Loads
If you page only loads partially then this could be a php error. If you see an error message then can you include this in any forum post you make about the problem.
If you don't see an error message then temporarily enable maximum error reporting in the Joomla config. This is the 3rd option on the server tab. Then try loading the problem page again and include any error message you then see in your forum post.