What I do for invalid DVD structures is first rip to hard drive with DVDFab Decrypter. It will decode the entire DVD to the hard drive. The problem occurs when I try to make an ISO of it, usually with DVD Shrink. Shrink has a problem with the invalid data structure. The fix is simple, though. Download FixVTS, drag the problematic VOB into it, and run it for the entire disc. This will repair the data and allow you to burn it.

I will never use anything like AnyDVD or that I must pay for. The freeware exists.

But I don't think that this is molson's problem. I think something must be wrong with his DVD drive, such as a piece of debris wedged in there that is scratching his DVD.