HDMI Closed-Captioning won't go away

Use only the hdmi cord to hook it up and go to menu on the tv and select hdmi for hook up and you should get a picture. Make sure your cable cord is the only cord running to the cable box , you don't need any other cord.

I had the exact same problem on a brand new Insignia 26 " LCD with DVD. Comcast tech was able to fix it by changing the Comcast box diagnostics. Here is what he did. Using the Comcast remote with the TV on - press power, cable, menu in that order. A comcast diagnostic srceen will appear. Select Additional HDMI options, then audio options. Change the audio options to L-PCM. Press power again to exit the diagnostics. That will fix it and you get to use the HDMI cable.

Had this happen on a Comcast box (Motorola DCT 6416 III)
Here's how to fix it:
Turn the cable box off, leave fully connected. Press Menu on the remote
The cable box internal menu will display (Not the Comcast one the Motorola one-- i.e. Display ratios-16:9 etc It's in black and white)
Use the arrows to cursor to the Closed Captioning and toggle to "Disabled" Press Manu again to exit and Voila!

Power the box on an have at it

I had the same issue... here's what I did.  If power off your cable box, then press the menu button, there's a selection to enable or disable Closed Captioning.  This works for both HD series Motorola boxes Comcast offers, at least in the Minneapolis/St. Paul area.  Hope this helps!
Evan

Go the the settings on the cable box. look for output resolution, then change it to 1080i and 720p. now turn the box off and back on your tv will now display the input of wither 1080i or 720p depending on the hd channel your watching.