When I said "set up ethereal on a hub" I meant put all the computers on a hub and connect the hub to the linksys, (it's a switch). Then all the computers can see all the other computer's traffic. Then fire up ethereal on one of them. The packet capture should ID the iffy machine by the mac address of the source machine. Then it's time to turn off the other machines and ethereal all packets on the network, (you can't filter on a mac address in ethereal as far as I know). Then you can work from there......