[sR Craig]

Try this... I bolded areas i changed...

RewriteEngine On
RewriteCond %{HTTP_HOST} ^YourSite.com$
RewriteRule (.*) http://www.YourSite.com/$1 [R=permanent]
#RewriteBase /
RewriteRule ^((urllist|sitemap_).*\.(xml|txt)(\.gz)?)$ vbseo_sitemap/vbseo_getsitemap.php?sitemap=$1 [L]
RewriteCond %{QUERY_STRING} !vbseourl=
RewriteCond %{REQUEST_URI} !(admincp/|modcp/|chat|cron)
RewriteRule ^(.*\.php(/.*)?)$ vbseo.php?vbseourl=$1 [L,QSA]
RewriteCond %{REQUEST_FILENAME} !\.(jpg|gif)$
RewriteRule ^(archive/.*)$ vbseo.php?vbseourl=$1 [L,QSA]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !^(admincp|modcp|clientscript|cpstyles|images)/
RewriteRule ^(.+)$ vbseo.php?vbseourl=$1 [L,QSA] 
php_value memory_limit 32M