Cannot send PM - $notfoundhtml

[Mean]

My .htaccess code is this

Options +FollowSymlinks
RewriteEngine on
RewriteRule ^([a-z0-9_\-]*-(f|all)[0-9]+(p[0-9]+|/index[0-9]*)?\.html)$ forumdisplay.php/$1 [QSA,L]
RewriteRule ^([a-z0-9_\-]*-(t|p)[0-9]+(p[0-9]+|/index[0-9]*)?\.html)$ showthread.php/$1 [QSA,L]
RewriteCond %{REQUEST_URI} !(index\.php|\.css) [NC]
RewriteRule ^(archive|sitemap)/(.*)$ $1/index.php/$2 [QSA,L]

And there is nothing any vbseo file or code. Maybe vbseo has changed some settings in vbulletin. Can you give advice about how can i get rid of that ? Or where is the coding which Vbseo has changed ?