Yup - I have the same problem. Got an LN52A860 and also get the flickering when using the component cables and setting the Wii to 480p. 480i works flawlessly using the same cables. To be honest - I can't see that much of a difference between the 480i and the 480p displays - - - must be my old eyes!!
Probably read the same forum messages as you as other people are having the same problem. Haven't figured out the cause yet nor a solution.
wii 480i works OK. wii connected to TV by component cable. Both component input behaves same way. I had owned multiple 750s, it used to work like charm. When wii output (Screen Resolution) is set to 480p, the screen flickers and after few secs 'Mode Not Supported' message appears.
Main board was replaced. But no avail. Same problem. In avsforum, members reported the same problem.

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