Methods and program products for communicating file modifications during a collaboration event

A conferencing system comprising:

• a data network having at least one network computer for communicating real time conference data between a plurality of user computers;
• a plurality of user computers connected to the data network, each of the plurality of user computers configured to transmit streaming data to all others of the user computers over the data network, and at least one of the user computers receiving the streaming data from others of the plurality of user computers over the data network;
• a shared file stored on the data network, the shared file having a current property;
• wherein at least one of the user computers is configured to communicate a shared file modification status request to the at least one network computer, the shared file modification status request including at least a file identifier identifying the shared file and a property;
• and,
• wherein the at least one network computer is configured to receive the shared file modification status request from the at least one of the user computers and to perform steps comprising:
• identifying the at least one shared file;
• identifying a current property of the at least one shared file;
• comparing the shared file current property to the property from the shared file status request;
• and
• communicating a response to the at least one user computer that transmitted the shared file modification status request when the file current property does not match the property from the shared file modification status request.