Hi, I posted the same question in Blender Artist but I haven't got a response yet. So, I'm trying my luck here as well.
I'm trying to render just simple particle hair with child under blender 2.64a and I get different result between the 32-bit and 64-bit version of blender under Ubuntu 12.10.

Images are upload at this post. The 64-bit blender seem to add some strange highlight to the hair while the 32-bit version seem to have a nicer over-all result.

Originally, I tested the 32-bit blender under 32-bit version of Ubuntu 12.10. I tested it out further and found out that even when under Ubuntu 64-bit version, using ia32-libs and blender 32-bit 2.64a, the result is still the same as the 32-bit image. But under the same machine with same OS, if I use the 64-bit version of blender 2.64a, the result is like the 64-bit image.

Am I missing something, like some setting here?

Thanks in advance.