If it's happening on all sources, you might want to exchange the television (depending on how brand new it is). If that's not a consideration, you can get the unit serviced as well.
If it's only happening on the television source (and not the DVD, game console, etc), then it may be a setting or an issue with the cable box.
Keep me posted.
I am not sure if its a picture settings issue or the malfunctioning of the TV set... unless the "black light" setting is set to "10" the picture flickers when watching TV on my HD cable box. Setting it to 10 seems to resolve the issue but even then on black pictures during a commercial for example the flickering becomes noticeable again. Also on start up the picture will flicker from anywhere between 5-10 seconds. Any insight would be appreciated. I live in Canada btw...