Error Message when trying to update reservation calendar

When ever I try to update and make a change on a reservation, I get an error message that says, Sorry, message stream has failed, contact support". Then a white square appears in the center of the screen with a circular wheel with black spokes just keeps spinning and there is no way out unless you either close down the calendar or hit the back button. What is causing this? Why won't the update take affect?

I'm using the current Firefox, as it will not work with my Explorer.