I am connecting the HDMI Cable to the HD Box and it does not provide a picture. I does flash a DUI code when it tries to connect via the cable. Does this mean I have to upgrade my service to HDTV for the box to work as an HDTV Box and the HDMI cable will then produce the signal I need for the rest of the devices?
No. It means that your TV and the STB have a failure ot communicate. Search for "HDMI Handshake" and you will find multiple posts regarding this problem with the Motorola boxes. The boxes (HD or SD) always have all the video / audio outputs enabled at all times. Also, ALL of Verizon's tiers include some HD. Supposedly there will be a firmware update at some time in the future to fix this known isuue (it is less prevelent than it was on the previous firmware version).
The only solution (really a band aid) is to use component cables (red / gree / blue) for video and red / white for audio. This will still give a full 1080i HD signal.
Are you getting sound but no picture? Is the TV set to HDMI input that the STB isconnected to? It may mean that your TV does not support the resolution the box is putting out when the HDMI handshake occurs. (Some have reported this on other forums.) For example, some do not support 480i and the handshake fails. You might try tuning first to an HD channel (one above 500) and see if your TV sees that, If it does, set the SD Override option in the video options to "off" so that the STB does not output 480i signals.
FYI the "DUI" is really 'DVI" which is the STB indicating that the negotiation is underway.