For the record. I have fixed the erronous login to homepage problem. This is not in reference to the form login code found in the welcome panel but a direct permission problem for closed pages.
The problem presented itself like this:
url > http://www.mysite.com (homepage)
Standard error login form, login crudentials, login > "wrong path to login.php"
Solution, edit standard_error_template and replace:
Perhaps this will helps someone else out there, even though my thread title makes absolutely no reference to the problem