You may want to connect the player that isn't working with a composite cable (yellow video) to see if the settings are set properly. In the cases of "Mode Not Supported", this usually has to do with a resolution that the television doesn't accept. Changing that setting in the player will likely allow you to choose 720p, 1080i or 1080p - resolutions that the television does accept.
I just got a Samsung PN58B860 tv, and I have both a Blu-ray and High Def dvd players, but when I try to play a hi-def movie, it says Mode not supported. What do i need to do for make it pick up the signal. Thank you