Disintegrate is one of the examples used in the description of Absorbtion in complete arcane, yet the spell also clearly states that absorbtion doesn't work on effect spells. Disintegrate is an effect spell, specifically a ray.
It doesn't. The example is in error, as has happened before. The example of Spell Turning in the PHB, which Absorption is a stronger version of, originally had Inflict Critical Wounds as an example spell being turned, even though it cannot be. That was later errataed to magic missile.