My Mac will mount my windows box just fine, but treats Samba shares from my unix boxes differently. If I make a shortcut to the share (drag the icon to the right side of the dock) it will mount *once*, but after that if I unmount it the next time I click the shortcut I just get the question mark icon superimposed on the link. I can explicitly mount it with shift-k or whatever and it is working... It's just the shortcut that is broken and only after the first mount/umount.
It's always been this way... I kept hoping that some update would fix it... but no. I think my Samba server is up to date (it's whatever came with Redhat 8.x on my linux box) and does the same with samba on my Solaris box.
I know I can use NFS for these boxes, but UID mapping or authentication is a pain and I've already got samba set up.