Maybe this might fix your problem without needing to cut the file up...
The smb file system driver in Linux 2.4 has a 2GB size limit.

Actually, according to the samba team, the 2Gb limit is actually if you use
mount -t smbfs command which is not within the scope of samba. they
recommend using smbclient.
found here http://www.redhat.com/archives/fedor.../msg00173.html