Created attachment 160094 [details]
Output of GVFS_DEBUG=1 /usr/lib/gvfs/gvfsd -r

Probably this question is more related to samba functionality than to Nautilus.

Seems that nautilus doesn't support copying files larger than 2 Gig from a samba share.

The following error occurs when 2 Gig is copied:
Error while copying "xxx".
There was an error copying the file into xxx/xxx.
Show more details: Invalid argument.

I attached the output of 'GVFS_DEBUG=1 /usr/lib/gvfs/gvfsd -r'. I deleted all the repeating GVfsJobRead debug info otherwise the dump would be over 2 MB with useless data. I left the beginning and the end unchanged.
I started logging just before I did the following:
Go to: Places -> Network -> [server] -> [sharedfolder]. Then I dragged the desired file to my Desktop.
The same error occurs when i use gvfs-copy.  

I had to manually mount the share with lfs option to succesfully copy a file with a size of aprox. 4 Gig.

kind regards.

Ubuntu 10.04 LTS - the Lucid Lynx, Desktop
Nautilus 2.30.0, package: 1:2.30.0-0ubuntu4
gvfs 1.6, package: 1.6.0+git20100414-0ubuntu1

I reported the same bug for Ubuntu 9 at https://bugs.launchpad.net/bugs/510938.