Your ASP.NET website is in a nested virtual folder underneath your Ektron CMS400 installation folder. For example, your Ektron 7.0 install folder is /CMS/ and your website is located at /CMS/Website/.
After upgrading to CMS400 7.5, integrated editing no longer works. You no longer get the green border or the white editing bubble.
The session cookie for the CMS no longer matches the session cookie for the site.
Create a page on your site that contains three things. One, an IFRAME pointing to the login.aspx file in your Ektron CMS400 folder. Two, a button that calls in order in the code-behind the functions Session.Clear() and Session.Abandon() in that order. (I've tried them individually, but for some reason, it takes both of them for this to work in my testing environment.) Three, a link back to the home page of the site you want to edit.
Log into the CMS through your IFRAME.
After logging into the CMS, click the session kill button.
After clicking the session kill button, click the link back to the home page.
You'll have your editing environment back.