Cisco Cable Box stuck on "Downloading Initial Application"

First problem was that many of my HBO and Showtime HD channels were not working. They started off becoming pixelated and then progressed to just showing an error message. I put in a service call, and they replaced the box. But now, the box won't get through the reboot cycle. It progresses to the point where it says "Downloading Initial Application" on the screen, with an APP on the front of the box. Any ideas? I've tried disconnecting the power and rebooting multiple times. Is there an issue with the signal?