Options +FollowSymlinks 
RewriteEngine on 
RewriteBase / 
RewriteRule ^([a-z]+).html$ /index.php?$1 [R,L]
RewriteRule ^([a-z0-9_-]*-(f|all)[0-9]+(p[0-9]+|/index[0-9]*)?.html)$ 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]

Options +FollowSymLinks +MultiViews
RewriteEngine On
Rewritebase /
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]
<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>