BleepingComputer.com: Unknown Computers in Trend Micro

My OS is Vista home premium, security is Trend Micro Internet Security Pro. In the past week using the home network function in Trend Micro, unknown computers have been showing up, I now have twelve unknowns blocked using the network map function, all have different IP addresses, some are close in numerical sequence. I don't know what other info. would be needed to figure this out, how can I get out of this mess. Scans in safe with Trend and Malwarebytes show nothing, Windows safety scanner shows nothing, no open ports. I have run threatfire, nothing. Don't know what to do, any help would be great.