Why does my calendar randomly set appointments itself?

[Tom M]

All through the day, my calendar randomly outlines times, as if self
scheduling. It will do this in blank time slots or occupied ones. Something
is wrong. Cleaning this up constantly is a nuisance.

 

[Vince Averello]

Are you running any third-party tools that might be causing this or sync
products that might be malfunctioning?

 

[Brian Tillman [MVP - Outlook]]

All through the day, my calendar randomly outlines times, as if self
scheduling. It will do this in blank time slots or occupied ones. Something
is wrong. Cleaning this up constantly is a nuisance.

What view? If you look at a day in the day view, for example, and click on an
existing event, then go to another day, that time slot will remain selected
even though nothing is in that time slot.