Problem has been identified but not fixed yet

1 - I installed KiXtart 2010 4.53 and it behaves the same way
2 - If user A logs onto B's copmputer, the Z: is mapped
3 - If user B logs onto A's computer the Z: is mapped
4 - if A or B log onto their computer the Z: is NOT mapped.

It looks like there is something in the profile that prevents the "Ingroup" to properly identify if the user really is in the group.

Why does InGroup do that ?

Thanks