OK, so I got this sorted... It was an .htaccess issue. I just dug around in the forums and pieced together these rules based on forum posts:
Options +SymLinksIfOwnerMatch
RewriteEngine On
RewriteBase /
# Fix Apache internal dummy connections from breaking [(site_url)] cache
RewriteCond %{HTTP_USER_AGENT} ^.*internal\ dummy\ connection.*$ [NC]
RewriteRule .* - [F,L]
#Redirect
http://www.mysite.com/index.html to
http://www.mysite.com/
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /index\.html\ HTTP/
RewriteRule ^index\.html$
http://www.mysite.com/ [R=301,L]
#Redirect
http://www.mysite.com/index.php to
http://www.mysite.com/
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /index\.php\ HTTP/
RewriteRule ^index\.php$
http://www.mysite.com/ [R=301,L]
# Exclude /assets and /manager directories and images from rewrite rules
RewriteRule ^(manager|assets)/*$ - [L]
RewriteRule \.(jpg|jpeg|png|gif|ico)$ - [L]
# For Friendly URLs
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?q=$1 [L,QSA]
RewriteCond %{HTTP_HOST} ^mysite\.com [NC]
RewriteRule ^(.*)$
http://www.mysite.com/$1 [R=301,L]
