I've tried to change
admin panel URL of my Magento site replacing
<![CDATA[new_admin_url]]> in app/etc/local.xml file.
I have only this issue: when I
login, the startup page (dashboard in my case) gives me a 404 Page Not Found (this is the URL:
http://mywebsite.com/index.php/admin/new_admin_url/index/noRoute/key/008cc1001579efd08067c36c315f293e/). After that I navigate in the
admin panel and all works fine. It seems the system doesn't find the correct route.