Most of the time I switch between inputs on my Vizio the sound turns off. It seems to be related to switching between HD and non HD formats. Is there anything I can do to solve this issue?

I have the exact same problem. It may be the tuner board is bad. I did some research and it seems like this tv is junk. I saw a link that said call Vizio and they are aware of all it's problems and are willing to give a new tv free of charge. I called and they knew nothing about it, but did offer to fix it out of warranty for $285 all problems fixed out the door. Also, TV locks up on RGB input and can't switch inputs until I hooked a computer to the RGB input, then I was able to select a different input.
Please post if you found a solution to the DTV issue..

I am having the same problem with my 42" vizio tv. When plugged in the standby light is on and when turned on the light switches from orange to white, however there is no sound and no picture. I am hoping to find what is wrong with it so i can get it fixed. Or atleast by the correct parts! I have only had my tv about 2 years

If the picture size isn't changing with the television's picture size adjustment setting there could be a few things going on. Check to see that you're in the right input on the television i.e. if you are connected to a high definition receiver make sure you are not in the tv/tuner input (tv display would say analog channel 3 or 4). Make sure your tv is switched to the high definition input i.e. component 1 hdmi 1 and etc. If you are in the high definition input already check and see that your cable box or satellite tv receiver is set to the proper resolution. For example if you have a 720p television make sure the cable box is set to 720p not 1080i. Last but not least look for the hd zoom # button on the cable remote. The button may also say format or aspect.

It is unfortunate that there isn't just one standard size or format, by which all programming is sent.

Programming format (size) varies from program to program.

Is it autosearching for an input?

I have a Vizio. If I use the HDMI input I can only get normal and zoom w/ picture buttom on the remote but get full picture on all cable supplied HD channels but not on none HD channels. However, if I switch cable input, I have the TV set up with both inputs from the converter box, I am able to have the options of normal,panoramic,wide and zoom on all non HD channels. I don;t like the black bars top and bottom of the HD channels with this imput mode so I switch back to HDMI. Maybe your TV is simmilar.

I am having the same issue. I believe the issue to be somewhere in the transition between HD channels and non HD channels. A work around is to switch the input to another input such as DVD and then switch back to your cable input (mine is the HDMI input). I'm probing the web looking for why this happens and if there IS a permanant fix.

For me it was the cable box settings...

I'm not a tech person, so take this for what its worth. I had the same problem with my Vizio and my Time Warner Cable HD/DVR box using the HDMI cord connection. HD channels were always fine, and non HD channels were fine until I went to an HD channel and back. When switching back, the non-HD channels would be shifted to the left as you describe. After much back and forth with both Vizio and Time Warner (each saying its caused by the other), I stumbled across the following fix...

I went into the cable box (scientific atlanta 8300) "settings", under "display," under "output resolution." There was a list including 480i, 480p, 720p, 1080i, and "auto select." I unchecked both 480 options and left 720 and 1080 checked. Problem solved. The other "Display" menu settings are as follows: Picture Size = Stretch, Aspect Ratio = 16x9.

Hope this helps.

there should not be a special setting that you need. When hooking the analog audio to the HDMI 2 input, it should read automatically. Note: The HDMI Input is for HD Video and will only support 640x480 at 60Hz from a PC. Use the RGB
PC input for a greater selection of PC formats.

or antenna try ch 5 ch 12 re auto scan the chs in menu again readjust antenna