Start by visiting our online demo at http:///www.cfdev.com/activedit/demo/edit.cfm
If the editor loads from this location, the problem can be found in your ActivEdit instance. The inc directory must be a physical directory under the same document root as the application and it's best to use a site-relative value (/pathToInc/) for the inc attribute, as form pages may reside in any sub-directory.
If the editor in our online demo displays the same error, disable Norton AV or Personal Firewall while using ActivEdit.