samba - strange problem

I have strange problem I never heard before. We have here LAN with 40 Windows machines, and my SUSE 9.2 box is only Linux computer. I can see all Windows machines and they see SUSE box. I can copy from them, and they copy from me. Everything is fine, but whenever I copy file larger then 100 MB, copying stops somevere about 100 MB. It seems like Samba have some limitations? When I turn off Samba server, and only Samba klient is up, I can copy big files. But other Windows machines can't copy from me, they don't see my computer. If you have some idea what's the problem, I will be gratefull. -- Mirko