Suddenly, I can't login to ALM, even though my user name is valid and shows up in Site Administration. I am getting a 'User does not exist error. What could be wrong?

Please review the ALM 15.50 Installation and Upgrade documentation.. here: ALM Installation GuideGo to page: 135 of 190.At that point there is almost no help with what you CAN or CANNOT do with the "features" I am interested in using:1) Customizing the ALM Login Window (would like to use it to put a...