If a long operation is not finishing (you can verifiy this by looking at the logs in Officity and noticing a 'onData src undefined' message), for example exporting your whole database of contacts in CSV or saving categories, it may be the server is giving a timeout before achieving the operation.

First check the PHP timeout is high enough. 10minutes (time_limit=600) is a good value.

If you are running Officity on a windows server with IIS, be sure to configure the CGI Timeout in IIS. See here for more explanations.