We're seeing a number of users complaining of problems creating appointments.
Appointment displays on wrong time slot
Problem: An open appointment has the correct time but it displays on the calendar as occurring "now".
When Outlook has an appointment on the calendar in the creation or received time period, it means the view is messed up. Reset the view to fix it.
Appointment can't be saved
When users receive an error that an appointment can't be saved, clean up (or delete) the forms cache and reset the view.