403 forbidden error when using multiple hyphens in page slug

I’m getting a 403 forbidden error when I try to visit a newly create “page” which has multiple hyphens in the slug (ie. http://www.mydomain.com/about-blue-widgets/). I “think” it’s a mod_rewrite issue. My current permalink structure is: /%postname%/

…and my htaccess has this code (generated by WP):

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

If I only use ONE hyphen (ie. http://www.mydomain.com/about-widgets/), the page works fine. Two hyphens gives me the 403 forbidden errors. Changing the hyphens to underscores (ie. http://www.mydomain.com/about_blue_widgets/ makes everything work fine also.

Any thoughts?

Thanks.
-G