There is an update to this old thread.
1. That receiver died. However, when I replaced it with a new D12-100, I learned that the dying receiver was not the reason for the extended time to get a picture.
2. If the receiver has been off long enough to not have the program guide stored, it will download the program guide again. The notice on the TV screen says it may take up to 3 days to fully download. What the Directv rep told me is that during that big download, the screen update on channel changes is extended due to limited bandwidth issues.