ok just a quick check,
not wanting to make you look dumb or anything but there are different versions of max within each version..
i.e.
a.Single workstation license
b.stand alone workstation license
there is a subtle difference...
if you try network rendering with a standalone license it wil not network render no matter what you try, however it will see and be seen by other ws's with max installed, thats why the box is greyed out in most cases.
so first off check which license system is actually runing on each workstation, and also i am pretty sure that the demo (although fully featured is blocked on network rendering)
also check permissions on the system running max; i.e. is it allowed to have remote systems running processes on it????
just a few thoughts, if i can think of anything else io will drop you a line ini in q, hope this helps some.
tom