problems with the Calender:no possibility to fill in details and to attach documents

problems with the Calender:no possibility to fill in details and to attach documents

Dear everyone,
we are using the zoho-calender for almost 4 years now. 
Recently we can't see "Details"anymore in the Calender. It's not possible to fill in extra information.
The framework for filling in extra information is not shown anymore while the system says it's loading.
Can anybody tell us how to fix this or is this a bug?

Sandra
The Netherlands