I would check to make sure that a new box doesn't fix the issue. I don't know why the co-ax wouldn't allow you to see the other sources, but I'm not aware of any firmware updates for your model that would fix that - but it might be worth double checking:
I have a Comcast HD Cable Motorola box (DCT6412 III) hooked up to my Samsung LNS40S41DX via an HDMI cable. I have had the TV for about 3 years. This is my 5th Comcast cable HD/DVR box in the past year. They are not reliable at all.
The TV is mounted on the wall and has not been touched except to tilt the TV or use the power button on the front.
Four days ago cable ceased to work. When the co-ax is plugged directly into the TV I get Non-HD cable, but the TV no longer acknowledges that an HDMI cable is plugged in: meaning, I cannot choose HDMI 1 or 2 via the "source" button on the remote.
I tried to plug the HDMI cable into both ports on the back, but neither seemt o allow me to use "source" to choose them. As of yesterday I could, and it would just say "No Signal" on a black screen, but today I could not.
Is this an HDMI cable issue, a cable box issue or is it possible that both HDMI ports on the back went bad simultaneously?
Also, if the HDMI cable is plugged into a faulty cable box and one of the ports on the back of the TV, would that cause it to not be selectable via the "source" button on the remote? Or is the TV broke?
Any input is helpful. Thank you.