>I have logic that disables other users from logging into the app. during the daily closing process. I simply log the current posting date to a control record at the beginning of the closing process and then clear it at the end. My only concern is if the user is in the middle of closing and there pc looses power or freezes up the user will not be able to log back into the system because of the flag in the control record.

How about just opening up one of the system tables exclusivly during this process? If another user tries to log in, they will get an access denied. If the processing computer bombs, the file is let go and teh users can now get in.