Originally Posted by ArtemisGregory
Unfortunately unplugging it for an extended period did not work. I contacted Dynex via email and they actually suggested the very same thing. I'm completely stuck.
You need to check the resolution that is being output from your cable box. Select an HD channel on the cable box. On the TV remote, press the Info key. You will get a momentary display across the top of the screen. The resolution data will look like "HD 1080i HDMI", or something else. If 1080i is not shown, then you need to set the cable box to fix that problem.
When using the digital output from a cable box, the box can sometimes lower its resolution to what the box has determined the TV can support. If this happens, the change is permanent until the box is reprogrammed. Fortunately, you can do the reprogramming.
Contrary to an earlier post here, use of "On Demand" from the cable box can cause unexpected behavior of the box. On Demand uses a completetly different means of communication and control than does normal channel viewing. Hiccups are fairly common.
Since you already reset the cable box to default settings, I assume you know how to change the settings. The "defaults" may not be what you were using originally. The box may have been set to 720p originally, or the 4:3 (standard definition) could have been on 480i, 480p, stretch, or "none" (which will output SD channels in the selected HD resolution). On some boxes, "Pass Through" may be available as an option for HD and/or SD. This will output the original broadcast resolution for each channel.
My own preference for SD setting is "none". This will usually produce the best looking SD display, and the SD display will also be wider (with the proper aspect ratio). And the TV never has to change resolution when changing channels, so you do not get the associated delay or picture jitter.
You can play with the SD option to see which one you like best.
Use the Info display on the TV to make sure you are actually getting what you thought you selected in the cable box menu.
The chances that anything happened to your TV to cause your problem are low. The chances that something changed in your cable box are much higher.