I have solved this problem for me... and hopefully this will help out others. If you check-out the following link you can follow along on the frustrating journey....
https://dnntracker.atlassian.net/browse/DNN-5467
What it turned out to be in the end is an improper assignment for the AdministratorRoleId in the Portals table. For some reason which still defies understanding the RoleID generated for the Administrator Role for my first portal was 0 not 1 as you might expect.
Later in the process, because of some comments made by another user having similar problems, I opened the Portals table to check the RegisteredRoleID assignment because this seemed to correct his issue. Mine was correct, however, right next to it I found that the AdministratorRoleId was assigned to 1.
After changing this to 0 and restarting the application I am now able to access page settings, module setting, etc.
Hope this helps others find the issue.