Your problem probably lies in the properties of your connection of your computer to your network. The first time you hook your computer you'll be asked which kind of network it is. If you choose the first option, then the other computer in your network are not trusted.
So open your properties of your network(connection) of your computer, make it a kind a e.g. companynetwork an reinstall beplayer. There is are difference were windows XP or 7 different works with networks. XP was more naive on that point.