Since Thursday or Friday, NBC HD has legacy analog copy protection flags set, which is preventing it from being recorded on my Windows Media Center based DVR (not sure if FIOS own DVRs are honoring this flag, probably not).
There is a beta firmware to ignore this legacy flag, but trying to use it made my tuner card extremely unstable (I was afraid it was bricked until it stayed up long enough to revert it back!)
Tuner web interface showing the copy protection is attached.
It's against FCC rules for cable providers to copy protect local broadcast stations, my guess given the CGMS flag used is this is actually the local NBC station getting it errantly stuck set from some commercial. Doing a web search it seems to have happened about the same time last year.