I
hate when that happens!!!
I had the Lost In Space TV series first season dvd which had a flaw on the disc that caused one episode (my favorite one, of course, "Mr. Nobody") to freeze and skip back to the beginning !!!
I returned it way back when and still have not opened the replacement, and sadly, expect the error to be there again, though I haven't yet looked at it (and I'm talkin' years since I replaced it!)
I also bought a 4 movie collection of Roger Corman off of Amazon that should have included
NOT OF THIS EARTH, one of my favorite Corman films,
and it is not included !!!