server returns 200 OK code for non-existent page

[d2a]

Odd one - checking my header responses from my GS3.0 site, I get a 200 response to a non-existent URL. that can't be right can it? i've checked and most mentions of this problem date back to v2, and appeared to have been fixed.

i have a modified install of the news-manager plugin if that's a factor.

my installation is in a sub-directory called cms with an htaccess rule to remove that directory from the path, and another to redirect the root home page to a specific page:

Code:

# Remove CMS from url
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d [OR]
RewriteCond %{REQUEST_URI} =/
RewriteRule ^(.*)$ /cms/$1 [L]

RedirectMatch temp ^/$ /projects/

the site url is [EDIT] and a non-existent path could be perhaps /jabberwocky/ or /cms/jabberwocky/. both respond as 200.

any thoughts on what i need to try to fix this? thanks...