This from Oakland, CA: A couple of days ago we lost ALL local PBS stations (9, kqed 22 kqec, etc).
All that shows is a garbled screen (with CBS logo at bottom, and occasional sounds, though mute is on). Then a message saying (not exact quote) Try again later, there is a problem on OUR end. Service technician (offshore) tried resets, disconnect cables, etc, then we lost internet connection w/ him. A few months ago there were notices about certain Sony DVD receivers (ours is a recent model Blu-Ray) causing problems due to channel changes, but we did not need to worry when these went into effect. Now can't tune in ANY public tv stations.
I think the problem is on their end - a number of stations recently had to change their over-the-air frequencies, and Comcast has to do something on its end to get the channels back.
Strange - I am in Solano County, and I get all of the PBS stations (KQED 9, KQEH 54 (actually, it's channel 10 here), and KCRB 22 - note "KQEC" hasn't been on the air since 1988 (its non-PBS station KMTP 32 now)).