The glass material is a standard blinn with a dielectric_material connected to the mentalray material shader (in the blinn's shading group) with a dielectric_material_photon connected to the photon shader. I also tried to set the glass as a 'L-Glass' shader, but had similar results.

If I had to guess it would be something amiss with the refractivity, I set the mentalray settings to production quality with 10 for both reflections & refractions.

Any suggestions would be great, I'd be happy to explain the shader setups in detail if need be.

Thanks,
Dave.

PS: Just a thought - would rendering out in layers make any difference??