I connected my HDMI cable to my television and have comcast for my provider. I get the HD Channels beautifully but when I go to a regular non HD channel, I get no sound at all, only the picture. How am I able to use both the HD channels and also regular channels?

The HD channels will require using a HDMI or other suitable connection regular cable input will not allow HD channels

No HD channels on a DCT700, you have to have a HD capable box from comcast. Usually $8.95 a month for box rental. Don't know a lot about DVD players. If you get a comcast HD box, and have an HD TV, you should use an HDMI cable for best picture. Second choice is component cables. Those are the red, white and yellow or red, white yellow, blue and green cables.

I removed the HDMI cable and connected with component video and rca audio. No more white screen.

Picture quality looks good. I don't know if it's as good as HDMI, but then I don't need to reboot the TV three times to get to teh on-demand menu... Grrrrr....

I am trying to contact Toshiba on this as well. I have seen several reports of this problem on the web.

To get an hd picture you have to use a digital input and this cannot be done by simply turning it to a channel. You need to hook up your HD receiver (box) to your tv using either an HDMI or a Component which will be a cable that looks similar to an rca but there are three of them and the colors are bed blue and green. If there is a red, blue and green on the back of the cable box and the tv hook them together with a component cable and then find the input on your tv that correlates to the compnent connections and then even after all of this you need to be tuned into a channel that is offered in high definition and if you have cable like I do the high definition channel will be a seperate channel from the regular one. Comcast in my area puts the HD's from channels 400-500. For example my espn HD is channel 403 but just regular espn non HD is on channel 27 in my area.

The link below echoes that it is a tv issue, not an issue with the box.
http://www.fixya.com/support/t1314756-no_non_hd_sound

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.

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.

Okay,i assumed this is what you have:
HD cable box with HDMI cable connection to the Samsung TV.
Listen careful as follow:
First you want to make sure using the same HD comcast box with HDMI connection for our Samsung TV as well as your other TV.Be sure the other TV do received the missing channels from the Samsung TV.You must be SURE you have tested both TVs with the same HDMI cable with the SAME HD cable box.
Now that you have confirmed the both TVS are using the same HD comcast box and the same HDMI cable but the connection that goes to the Samsung TV are missing some channels,at this point,use another HDMI connection behind your Samsung TV and see if you have the same problem.If so,please also try the left side of the HDMI connection and see if you could get the other channels.
Let me know!
solutiondoct

I had the same problem
you have to set up the componant on DTV.
the signal my be hd 1080i and the only connection with componant that can support this is the DTV port.
the other componant connections only support 480,
good luck

Set your 4:3 to stretch mode, see this link

www.hightdefforum.com/showthread.php?t=24734