I was trying to play a DVD on VLC, I couldn't get it to play, due to "can't seek to block" errors.
So I moved on to SMPlayer which sometimes can play discs. I didn't like using SMPlayer for this one because for some reason if I'd skip ahead beyond a certain point the player would fail.

I then tried VLC and had no luck(it would not play at all), but then someone suggested when you go to "Media->Open disc" hit the checkbox "No disc menus" before you use the "Play" control. This solved my problem. Apparently VLC is trying to read on disk menus and failing for some reason.