QuietSimple upgrade freezes at Upgrade Progress screen

I have a SQL Express upgrade running from a config file with QuietSimple=True.The upgrade freezes at the end of the  "Upgrade Progress" screen. It reads "Setup process complete" and shows "Database Engine Services" and "SQL Writer" installed successfully.The Next and Cancel buttons are grayed out.Any ideas why?Config file:;SQLSERVER2008 Configuration File[SQLSERVER2008]; Specify the Instance ID for the SQL Server features you have specified. SQL Server directory structure, registry structure, and service names will reflect the instance ID of the SQL Server instance. INSTANCEID="SQLEXPRESS"; Specifies a Setup work flow, like INSTALL, UNINSTALL, or UPGRADE. This is a required parameter. ACTION="Upgrade"; Displays the command line parameters usage HELP="False"; Specifies that the detailed Setup log should be piped ...