Recent updates to Outlook 2007 changed the behavior of tasks in the reminder window. In the past, reminders that fired at 10 AM showed due at 10 AM in the reminder window and an hour overdue at 11 AM.
Now, the reminder window shows the tasks due at the end of the workday (set in Tools, Options, Calendar options) so the same task that was overdue at 11 AM is now due in 2 hours.
This screenshot shows you where these times are seen:
Published June 24, 2009. Last updated on October 31, 2011.