welch1720,

As with any digital signal, the cable/sat boxes on the the market have an HDCP chip (copy protection) that has to determine that the signal isn't being used inappropriately. The symptom of an HDCP issue is that the volume remains, but the picture is held back.

When you switch different resolutions, the television has to reconnect to the new data stream that is being sent, and that may be what is causing this issue.

You might try calling the cable/sat company you use to have them update or reset the box to see if that alleviates some of the issue. Sometimes signal connection issues like these can be updated with software in the cable box.

If not, it may be an issue with the television where the signal has to change the way it processes the incoming picture, and that adjustment also may take a moment to initialize.

Keep me posted.

--HDTech