Problem copying large file over network

Trying to copy a large file to a network share (either a NAS or Samba share
on Linux) I see this message after about 5 - 10% of copy progress:

"There is a problem accessing C:\junk\myfile" (Note: This is the LOCAL
file)

"Make sure you are connected to the network and try again"

The file size is 27GB.

- It copies OK with FTP
- The PC is dual boot. If I boot to XP the same copy works OK
- I have applied hotfix KB922045 and this has made no difference.
- Small files copy OK

Any thoughts?

thanks,