Donna,
You have to be an active participant to stay in the chat room. This can be as simple as typing a "." every couple of minutes. Sometimes a person might leave the computer for a few minutes (retrieve some libation, scream at the kids, whatever) and the chat room thinks they are no longer active so it drops them. They sign back on as soon as they return. Sometimes, one might simply goof and hit the disconnect by accident.
Dave