I'm having the EXACT same issue. When I woke up this morning, my DVR box was automatically resetting itself, but eventually turned on. Now, whenever I try to access the Guide, Menu, OnDemand, or my own DVR, nothing happens. I can change the channel, but no information or guide is given on the screen. When I press Info, it asks for me to setup a parental controls PIN code. I spoke when tech support who ran me through the usual gambit of resetting everything (router, dvr box, etc.) but the issue is still happening. The technician is sending a tech out to my house tomorrow, but says it will cost me $95 per HALF HOUR if it turns out to be my coax cables and not the box itself. Seriously? After reading this comment, I'm pretty sure it's an issue on their end and has nothing to do with my box or cables.
P.S.. - As I've been typing this, my box has reset itself.... twice.
UPDATE: I'm back up and running....
What area of the Country.
IMG 1.9.4 just rolled out in Florida, and some of those symptoms occur when boxes are in the middle of an update.