I have the same Zenith DVB318 stand alone and experienced the same problem as you with Walk The Line. In my case it was worse, the player completely locked and would not even power down, I had to pull out the plug from the unit, plug it back in, then hit eject. You can rule out media, firmware issues as being the cause, it's the player itself.
I always use ClonedDVD2 and AnyDVD with jump to main movie and preserve menu's. As AnyDVD states jumping to the main movie or title may not work on all DVD's.
Out of over 400 backups I have only experienced this 3 times, the only time you would know it's a problem disk is after you burned it.
I can take this same disk and play it in my Sony stand alone in the bedroom and it works fine, the issue is with the Zenith player itself in how it reads certain disk structures, and not with the autoplay feature. I can enable or disable autoplay and it will lock in either mode.
Let us know how you made out with your test by unchecking trailer and advert option, let's see if this will correct the problem as Whisperer1 suggested.
My Solution: When I encounter this problem I simply watch the original on the Zenith or I can watch the backup on the Sony in the bedroom. I can also burn a DL disk and copy the movie in it's entirety.
Since this issue appears in only very rare circumstances, I can live with it.
I will continue to use the jump to main movie feature and preserve menu's.
If you are bored and want to read everything you ever need to know about the 318, click on the below link and put a pot of coffee on.
Zenith DVB318 Forum â€“ 4,950 posts
Zenith: Sticky DVB 318 â€“ 1,737 Posts
If youâ€™re interested, in post #1 it has a link for firmware that will make the 318 Region free. I have not used it or intend to.