Lower level of new "Logoff time <= logon time" log message
... from ERROR to WARNING, but log the human-readable logon time too. This condition can easily happen if the system clock is corrected (e.g. a few seconds via NTP adjustment) during a quick connect/disconnect. Don't call logoffstats() unless a user actually successfully logged-in. I don't think sysops actually want all the time bots sit at the logon prompt counted as "time online" in their stats anyway.