Coloring shadows is definitely the wrong approach unless you are trying to achieve a surrealistic scene.  IBL and IDL will 'tint' your shadows because of ambient lighting.  Self illuminating material typically is caused by either an active ambient channel or light emitting checked in the Properties panel.  In P9/PP2012, the diffuse_value attribute has recently been discovered to be out of whack with IDL; you need to reduce the value extremely low and use higher light intensities, or reduce the IDL intensity in D3D's Render settings to less than one (0.15 - 0.3) to achieve the same affect with no self illumination where mesh makes contact.