Fermat's Last Theorem
Vos Savant wrote in 1995, that Wiles' proof should be rejected for its use of non-Euclidean geometry. She said, "the chain of proof is based in hyperbolic (Lobachevskian) geometry", and because this geometry allows things like squaring the circle, a "famous impossibility" despite being possible in hyperbolic geometry, then "if we reject a hyperbolic method of squaring the circle, we should also reject a hyperbolic proof of Fermat's last theorem."