Windows 2000 network problem

I have an IBM Thinkpad with Windows 2000 as operating system and the network card is 3Com Mini PCI ethernet adapter.
My Problem is whenever i try to access to anything that is copy any document from the clients on the network which are Windows NT Workstation 4.0, my Windows 2000 gets hang.
I have installed Service pack 2 also for Win2k, still the problem is there.