Large File copy problem

I am managing a small network of 25 systems. it contains 2 Win2k Servers. When there are no other systems on and when only the 2 servers are working, Itried copying a file of around 5.3 GB from one system to another. The process starts as usual but during the final stages it starts showing the time remaining as a 6 digit number and the process does not complete even after some hours. I have transferred such large files earlier on the same configuration. This is a new phenomenon. Please help.