It sounds like a copy protect error. Are you sure DVD43 is current? I think I read where it would not be updated for some newer type CPs. Try AnyDVD and see. It has a 30 day trial. See if Recode or shrink will load with it running.
You could try the dvdfabdecrypter. They have a free version and is updated fairly often (but not as much as anydvd).