I just bought a sony dru-710a dual layer DVD burner a few weeks ago. Since then I have burned a bunch of data discs containing music as well as video for my archives. All of the music that I burned plays just fine when I play it directly from the disc and I have no problems when I copy the files to my hard drive for burning. I had a few DVD's saved on my hard drive that I burned as regular data discs. Now when I try to copy these *.vob files to my hard drive I get an error message saying, "cannot copy vts_01_1: data error (cyclic redundancy check)" It does not do this for every file - some of the files work just fine, but every single DVD that I burned contains at least one .vob file that will not copy. Sometimes I get a different error message saying "cannot copy vts_01_1: not a valid ms-dos function." I get the same errors when I read from my other dvd drive as well. I only have one DVD burner so I cannot test burn with another drive. Does anyone know what is causing my problem? Could it be a defective drive? Thanks in advance.