When it copies a disc, it makes a temp copy on your hard rive - default is your C drive - if you don't have enough space on your C drive, it can't do it. You have 3 options:
Set the copier to burn disc to disc (on the fly)
Clean up your C drive to create some space - although a DVD takes up much room!
If you have a partitioned hard drive - uninstall the DVD creator software and re-install it on a partition that is not your C drive (where your system files are), but where you do have enough space.