Hey Fuzz ,thanks for your help - after a forum search i found http://www.silverstripe.org/archive/show/53326 and changing my htaccess fixed this. smiles :)
### Mod_rewrite
RewriteEngine On
RewriteCond %{HTTP_HOST} ^domain\.com.\au [NC]
RewriteRule ^(.*)$ http://www.domain.com.au/$1 [R=301,L]
### SILVERSTRIPE START ###
RewriteCond %{REQUEST_URI} !(\.gif)|(\.jpg)|(\.png)|(\.css)|(\.js)|(\.php)$
RewriteCond %{REQUEST_URI} !/$
RewriteCond %{REQUEST_URI} !^/admin
# Redirect to add a trailing slash
RewriteRule (.*) http://www.domain.com.au/$1/ [R=301,L]
RewriteCond %{REQUEST_URI} ^/home/$ [NC]
RewriteRule (.*) http://www.domain.com.au/ [R=301,L]
RewriteCond %{REQUEST_URI} !(\.gif)|(\.jpg)|(\.png)|(\.css)|(\.js)|(\.php)$
RewriteCond %{REQUEST_URI} ^(.*)$
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule .* sapphire/main.php?url=%1&%{QUERY_STRING} [L]
### SILVERSTRIPE END ###