I and one of my colleagues were working on some project. I was having the MacBook and my friend was using the iMac. Then after spending some time on our work we realized that the some of the folders that were on the system were marked as shared. On top of that we were also able to see that the folders were shared by a third person that we even do not know. I immediately disconnected the connections and then stopped our work. Now the thing is that I do not want to have this thing happen again. I have the Linksys Wireless router for the connections and the operating system that is installed on both the Mac is the Leopard. I have given the information regarding the system and the router and I would really need the suggestions on how can I stop that thing to happen again. Anything in that matter will be really appreciated. Hope to have the result soon. Any help in the matter will be really appreciated. Thanks in advance.