The 'Thunderbird Start Page' is what is displayed in the Message Pane when you start up even if Inbox is selected. Unchecking means the 'Message Pain' will be empty until an email in Thread Pane is selected. If Thunderbird is starting and the mail account name folder is selected in the Folder Pane then you will see the various options that are available eg: Read Messages, Write a new message, ....'choose what to set up' etc. If you select the 'Inbox' or any other folder before exiting Thunderbird, then that is remembered in the session file and should open on that last opened folder when you restart Thunderbird. If that is not happening then do you have 'Cleanup' type of program installed eg: CCLeaner or WiseCleaner or even some Anti-Virus products now provide that sort of 'cleanup' of files? these products tend to cleanup temp files, session files, password files etc. Do not allow them anywhere near your thunderbird profile folders and files. They must be made exempt if you intend to use those types of products. They could be deleting the session file in your case in which case Thunderbird cannot work as you intend as you are deleting the session file.