From Matt Whitlock's Mind Over Matt'er at TechLore.com
I noticed this morning that my Comcast DCT-3416 Dual Tuner HD-DVR wasn't displaying its clock, something I rely on when playing with my daughter in the living room before starting work. Upon further investigation I discovered that none of the advanced functions of the DVR were available - no guide, no DVR menu, not even the menu. I got a picture and could change channels, but that was about it.
I ultimately thought the internal hard drive failed (even though I could hear it spinning), which would explain some of the behavior I was seeing. I unplugged it a few times, let it reboot, and nothing. "Time to call Comcast," I thought... though that's certainly not something I ever look forward to.