Well, fwiw, you aren't alone on this.
http://www.avsforum.com/avs-vb/showthread.php?t=1062343
http://www.avsforum.com/avs-vb/showthread.php?t=1029021
As to the cause/cure.... hard to say. I doubt it has anything to do with the cable, but keep in mind that almost exclusively, whatever "ratings" the cable has are just bs advertising hype. That doesn't take away from the fact that cables rarely cause problems such as this.
Here's one thread with a little more discussion on the topic. Try their suggestions first.
http://www.avsforum.com/avs-vb/showthread.php?t=1096101
Here's the official thread for that series of TVs. It's 42 pages, so you can peruse it at your leisure should you so desire. More than likely, this issue has been discussed at some length in the official thread.
http://www.avsforum.com/avs-vb/showthread.php?t=1008342