Check your view.  With the calendar as the active window in Outlook, go to
View, Arrange by, Current View, then I'd select By Category, although other
Views may also work.  This should give you your calendar in list form and you
can see the conflict icon in one of the columns.  To return to the default
calendar view, just repeat the process, only instead of selecting By
Category, you select Day/Week/Month.

Good Luck!

TBGG
TrueBlueGeekGirl