Glad to hear you got your copy made. Error 400 has been attributed to everything from a bad or damaged original disc to burner firmware. Seems it also can occur when a disc has a new form of protection that Fab can't handle without an update. I don't see how the burner or firmware could cause a problem so early in the process. If you are happy with just a Main Movie copy, you are fine. If not, copy the IFO files from the original disc and email them to fengtao at dvdidle.com, replacing "at" with @, along with a brief explanation of what was happening when the failure occurred. Are you clicking "FINISH" when the copy job is done? Some new users just click on the red X to close the app, and you have to click FINISH to delete the temp files and let DVDFab clean up and exit gracefully.