I have noticed that Server 2012 has a bug where copying large files between an RDP session fails:
Anything over a few gig and I get an “Error Copying File or Folder.” File copy of large files over RDP has always been a little shaky, and eventually Microsoft will have a fix, but in the meantime if you find yourself running into this problem you can get around it by copying the files using UNC paths.
In Windows Explorer type: \\servername\c$ and then copy your files from there. \\Ipaddress\c$ should work as well you just have to make sure windows firewall is open to file and print sharing between the two systems.