I have a Motorola Cable Box that exibits that same problem from time to time.
I can't get to my cable box at the moment, but when I can, I'll let you know it's model number.
By the way, I have Time Warner Cable, not Comcast.
However, I do suspect that either:
A) It is an intentional anti-HTPC pulse, as it only seems to happen during a
First Airing of a TV Series Episode, or a Movie.
B) CATV Companies, in general, suck.
C) The Motorola Boxes are defective...
D) It's a conspiracy by the CATV Providers and Hard Drive manafacurers to get you to buy more Hard Drives so you can have enough space to record Every Freaking Airing (Repeats) of your favorite shows in hopes that you can piece together enough 'Good Parts' so that when you archive them to DVD they'll be 'Watchable'...
Edited To add:
Sorry about that...
I didn't mean to go off on a rant...
I only have a few shows that do this to me, and it happens just often enough to irritate me.
Also, since I uninstalled the "AC3 Filter" that is reccomended to use at
www.divx.com , the chirps that caused a recording to freak out are happening very rarely now.
The drawback is that I can no longer Convert video files with AC3 Audio into a DivX File without going through some other programs to split it out, convert it to something else, then remux it.
I also can't watch Divx files that have AC3 Audio in them.
For regular old DVD Playback I have the nVidia video Decoder and aparently, it did not play nice with that third-party AC3 Filter that the Divx gurus reccomend...