Page Not Found Trouble

My wordpress site has recently started showing a “Not Found
Sorry, but you are looking for something that isn’t here.” error message on pages on my blog. Posts have been unaffected, as have child pages.

What could be causing this to happen? Is it the htacess file?

AddEncoding x-gzip .gz
AddType text/html .gz
# BEGIN WPSuperCache
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /news/
AddDefaultCharset UTF-8
RewriteCond %{REQUEST_URI} !^.*[^/]$
RewriteCond %{REQUEST_URI} !^.*//.*$
RewriteCond %{REQUEST_METHOD} !POST
RewriteCond %{QUERY_STRING} !.*=.*
RewriteCond %{HTTP:Cookie} !^.*(comment_author_|wordpress_logged_in|wp-postpass_).*$
RewriteCond %{HTTP:X-Wap-Profile} !^[a-z0-9\"]+ [NC]
RewriteCond %{HTTP:Profile} !^[a-z0-9\"]+ [NC]
RewriteCond %{HTTP:Accept-Encoding} gzip
RewriteCond %{DOCUMENT_ROOT}/news/wp-content/cache/supercache/%{HTTP_HOST}/news/$1/index.html.gz -f
RewriteRule ^(.*) "/news/wp-content/cache/supercache/%{HTTP_HOST}/news/$1/index.html.gz" [L]

RewriteCond %{REQUEST_URI} !^.*[^/]$
RewriteCond %{REQUEST_URI} !^.*//.*$
RewriteCond %{REQUEST_METHOD} !POST
RewriteCond %{QUERY_STRING} !.*=.*
RewriteCond %{HTTP:Cookie} !^.*(comment_author_|wordpress_logged_in|wp-postpass_).*$
RewriteCond %{HTTP:X-Wap-Profile} !^[a-z0-9\"]+ [NC]
RewriteCond %{HTTP:Profile} !^[a-z0-9\"]+ [NC]
RewriteCond %{DOCUMENT_ROOT}/news/wp-content/cache/supercache/%{HTTP_HOST}/news/$1/index.html -f
RewriteRule ^(.*) "/news/wp-content/cache/supercache/%{HTTP_HOST}/news/$1/index.html" [L]
</IfModule>

# END WPSuperCache

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /news/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /news/index.php [L]
</IfModule>

# END WordPress

Any help you can give is appreciated.