Same File Transfer Much Slower When Originated From One Machine?

Here is my brain teaser,One machine on my home LAN uploads files to other computers very slowly although the same file transfer originated from the other computer proceeds normally.Fundamentally there are four computers. Three run Windows 7 64-bit professional or ultimate. The fourth runs Windows XP service pack three.Zotac Windows 7 Mediacenter Windows 7,Deb Windows 7,Ben Dell -Windows XP All of the computers have one gigabyte ethernet circuitry and the switch is one gigabyte. I have used the same 1 GB file to to the testing using the straightforward Windows Explorer copy and paste functions.The computer named "Zotac" is a machine which seems to upload very slowly.Listed below are file transfer times between the C drives of the one gigabyte file. As you can see the same file transfer differs depending on which machine originates it. From Zotac to Mediacenter,uploaded from Zotac-seven hours,downloaded from Mediacenter -10 seconds,From Zotac to Deb Windows 7,uploaded from Zotac-seven hours,downloaded from Deb Windows 7-10 seconds!The Zotac machine seems to be able to upload to the Windows XP machine properly however. Interestingly the same file transfer originated from the Windows XP machine proceeds somewhat more slowlyFrom Zotac to Ben Dell-Windows XP,uploaded from Zotac 2 min.downloaded from Bendell -15 min.Because the same problematic slow file uploads from machine "Zotac" occur properly when originated from other machines I have to assume that the hard drive read write functions as well as the network infrastructure are operating correctly. There are no video streaming or other file transfers occurring on the network.