[Carnage]

Just a brief look at your htaccess, i think its somewhat wrong. Try this instead:

RewriteCond %{HTTP_HOST} ^(www.)?forum.xxxx.net$ [NC]
RewriteRule ^threads/([0-9]+)(?:/?$|(?:-[^/]+))(?:/?$|(?:/page([0-9]+)?)) showthread.php?t=$1&page=$2&%{QUERY_STRING}
RewriteRule ^members/([0-9]+) member.php?u=$1&%{QUERY_STRING}
RewriteRule ^forums/([0-9]+)(?:/?$|(?:-[^/]+))(?:/?$|(?:/page([0-9]+)?)) forumdisplay.php?f=$1&page=$2&%{QUERY_STRING}
RewriteRule ^list/([^/]*/)([0-9]+) list.php?r=$1$2&%{QUERY_STRING}
RewriteRule ^content/(.*) content.php?r=$1&%{QUERY_STRING}
RewriteRule ^widget/config/([0-9]+) widget.php?r=config/$1&%{QUERY_STRING}


RewriteCond %{HTTP_HOST} ^(www.)?blog.xxxx.net$ [NC]
RewriteRule ^/(index.php)?$ blog.php?%{QUERY_STRING}
RewriteRule ^/([0-9]+)(?:/?$|(?:-[^/]+))(?:/?$|(?:/page([0-9]+)?)) blog.php?u=$1&page=$2&%{QUERY_STRING}
RewriteRule ^forums/(index.php)?$ forum.php?%{QUERY_STRING}
RewriteRule ^blogs/(index.php)?$ blog.php?%{QUERY_STRING}