FTP and Windows 2000

Currently FTP internally with W98 no problem. Attempt to do the same on a W2000 machine, and files do not fully transfer. This happens at different places in the file and from different machines. Transferred a 24M file from mainframe to PC on W98- no problem. Transferred the same file from Mainframe to W2 professional machine – got 4.7 meg then 16 meg. Did the same transfer to w2 server and got 14.6 meg without any error message. Any suggestions?? Obviously seems to be W2000!
Thankx,Melissa