Don't have any problems here using Samba to transfer large files from a Win 7 mapped network drive to my T2. Windows 7 is 64bit which may or may not make a difference.
My share definition in smb.conf
My share definition in smb.conf
Code:
[Video]
comment = Video
path = /mnt/hd2/My Video
public = yes
writable = yes
browsable = yes
create mask = 0644
directory mask = 0755
hide dot files = no