try out putting to 50hz (instead of 60hz). I don't know if you can do that on a wii (don't have one).
Having said that 1999 is not that old, and should support 60hz (its the early 90s pal tv that were 50hz only).
I remember people having a similar problem with the ps2, back in the day, but since i never had a ps2, i don't know much about it.
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