On the afternoon showing this week, the picture has been ahead of the sound by maybe two seconds. Doesn't sound like much, but it's huge. I don't think I've ever seen such a mismatch for more than one episode of a show (excluding foreign language dubbings, of course).

Edit: it's bad on Newhart, too.

If you're using a converter box to get decades, try turning the power button off, on the converter box for 20 seconds and then turn it back on. I've run into that problem before and turning it off and on gets it back in sync. It's worth a shot.