I'm having the same problem. Yesterday, trying to watch the Laker game, my Samsung 160 would lock up whenever I tried to tune to 7-1 (KABC). It would refuse to tune in any station after that (both audio and video) until I unplugged it for about 15 seconds, and then powered it back on. Previously, I had no problems with any of the digital stations.
I'm having the same problem tonight (4/14). I usually have pretty strong signal strength on all the digital channels. In fact, even though my tuner is currently not showing any video on any channel; the signal strength for 2-1 is 93%.