I'm using version 12.10. When I do large file copy from windows network share it always hangs the copy process. Rest of machine is fine, just the copy process is hung. I connect to the share by launching home folder then clicking on the network section. From there I can find my windows share. I'm finding this very annoying as I have over 2tb of data to migrate from my old windows environment to Ubuntu.
To me it sounds like a case for rsync; there you can just resume the copy process in case it hangs or you have to reboot inbetween or whatever causes interruption.
The copy process itself is a bit slower, one should mention.
Further examples: http://rsync.samba.org/examples.html