Problem copying large files

[Mojak]

I notice that when I am copying files (5Mb and above) to the server that it hangs and just don't give any error message. I need to go to task manager and end the copying process. When I copy I can see some of the files if im am copying a folder. I also notice that the transfer of data in the network indicator icon also does not transfer much data as when i am copying small files.

Using windows 2k server and win2k client on a domain controller environment.

Any idea, thanks.