try using Nero to make a disc to disc copy, and don't choose the option of 'on the fly', as that is definitely prone to errors/failures when copying discs...i.e. make sure Nero makes a copy on your HDD, then burns the disc...if you only have one burner, then this is the ONLY route you can take anyways, as it is obviously impossible to burn directly to a disc when the source disc is in the drive...choose a burn speed of 12x or less, and see what happens...as of this date, I have had quite a high success rate when using the above procedure..I have made copies of all my windows OS discs (98se, 2kpro, XP pro, XP MCE), all my games discs, and plenty of other things using Nero, haven't tried to make a backup disc of a DVD movie yet, but I'm sure I'll do so one of these days (like when the price of dual layer discs makes the next major drop in price)

if that still don't work (or you have already tried directly making a copy as opposed to a disc image) try the free trial of WinIso