Did you ever make an appointment for a future date or accept a meeting request and it displayed on “Today” ?
This is caused by a corrupt view and the fix is simple – reset the view on the calendar. If you use custom views, you can try resetting just the view on the calendar, but if the problem returns, you’ll need to use the /cleanviews switch (and wipe out all custom views).
Using /cleanviews
In the Start menu, search field (or use Windows key+R to open the Run command), type or paste
outlook.exe /cleanviews
and press enter. Note, there is a space between outlook.exe and the /.
If you need help resetting views, see How to Reset the View on Outlook folders
Published January 25, 2010. Last updated on May 8, 2014.