It sounds like what it says: the connection to the machine that is hosting the shared variables has timed out. To know why, we need more details about the problem. Do you have a DHCP or do you have static IP addresses for all your machines? Does the host of the variables have multiple ethernet cards? Does the IP address listed for "My Computer" in the project view match what you think your host machine's IP address is?
Have you tried your project out on a private network?
Richard
Field Sales Engineer, New Jersey
National Instruments