Issue with new installation - doing certain tasks like sending test emails or adding users to a list results in a blank HTML page

So… I just installed version 3.6.6 and got things setup with the database et-al… it seems to be working pretty well until I tried to send a test message to a single email account (yes, that person was in the list)… and the once I hit the “send test” button it does a POST to the following URL:

Send Test

I can see in the Apache2 log that the POST returns a 200 so that’s ok… but I’m not sure why I see this.

Also, if I use the “import subscribers” feature under the subscribers area and select an existing empty list and type one email address and hit the “import emails” button… the same thing happens… a POST is done and that results in a blank page on the browser.

I’m sure something must be amiss in my installation but I’m not sure even where to start…

Any suggestions?