Problem backing up DVDs to Xbox HDD using dvd2xbox

I have tried to backup several different DVDs to my xbox’s HD using dvd2xbox, but have had no luck. It goes through the whole process and then when it finishes it pops up and says that 4 files were skipped and asks if you would like to retry… I have done two days worth of searching around on here and haven’t been able to find a solution so could someone please tell me what kind of n00b mistake I’m making???