So I want to clarify something: the TV never was connected via HDMI to the Samsung laptop during this time, and when you tried to connect one of your other two laptops after the fact, they won't connect, but the Samsung laptop that you never connected before is the only device that works. Did I understand that correctly?
Could you let me know what message you see on the screen when you connect the laptops to the TV with them powered off and then power them on with them connected?
I have a Samsung TV model number LN40D550 that I have been using without a problem for over a year. I frequently used my Lenovo laptop connected via HDMI to watch movies and surf the internet on the big screen. Last week I brought my business Samsung laptop home to do some work and connected to the network (not directly to the TV but the TV is connected to the router), since then none of the other computers in the house will connect via HDMI to the TV (my wife's lenovo and another acer also do not connect). When I plug in the cable the message changes from "Check Signal Cable" to "check connected device's power, cable connection and source selection", so the TV knows something is there but no video or sound. Cable TV works fine on HDMI1 but no laptops will connect on any HDMI port, EXCEPT THE SAMSUNG LAPTOP which works fine as soon as you plug it in.
I have tried all the ports, bought new cables, disabled Anynet all to no avail. Really annoying. Need help.