  We obtain high-precision limb-darkening measurements in five bands (V, V_E,
I_E, I, and H) for the K3 III (Teff=4200 K, [Fe/H]=+0.3, log(g)=2.3) source of
the Galactic bulge microlensing event EROS BLG-2000-5. These measurements are
inconsistent with the predictions of atmospheric models at >10 sigma. While the
disagreement is present in all bands, it is most apparent in I, I_E and V_E, in
part because the data are better and in part because the intrinsic disagreement
is stronger. We find that when limb-darkening profiles are normalized to have
unit total flux, the I-band models for a broad range of temperatures all cross
each other at a common point. The solar profile also passes through this point.
However, the profile as measured by microlensing does not. We conjecture that
the models have incorporated some aspect of solar physics that is not shared by
giant atmospheres.
