We’re seeing some questions from users whose appointments are missing from the Month view but their all day events are visible. If this happens to you, check the Detail level.
Outlook 2007 and 2010 have a view option called Details – it can be set on Low, Medium, or High Details. High shows all appointments and all day events, while Medium shows all day events and uses lines for timed appointments. Low shows only all day events and hides all timed appointments.
The purpose is to give you an overview of your days on the monthly calendar – in medium detail, noon is indicated by a line across the center of the day, with timed appointments shown as lines above or below noon. The thickness of the lines shows how long the appointment is. This way a person can glance at the calendar and get an idea of how busy any part of any day is, based on the lines they see, since the normal (High Details) Month view may show as few as three or four appointments and events per day (based on Outlook’s window size).
In Outlook 2007, detail levels are selected just to the right of the Day/Week/Month tabs. In Outlook 2010, the detail level is selected from the month button on the ribbon.
Screenshots are at http://www.outlook-tips.net/howto/details.htm