I had a similar experience, only I choose to keep the widescreen.
When the menu came up and I clicked on fullscreen the disk froze and would not proceed. Idiot, should have expected this because it was looking for something thatâ€™s not there. I did it just as a test in case I lend it to someone to view, and they want the fullscreen mode. Have to mark the DVD to only select widescreen. Unlike yours, when I selected widescreen it played just as it should. I never included the fullscreen since it took up too much space and quality would be lost.
Method used in CloneDVD,Copy DVD Titles, and preserve menus.
Moral of the story, whenever I come across disks that have the menu option for selecting formats, instead of putting the formats on either side of the disk, I must either mark them, or do movie only with no menu as not to confuse others borrowing the disks. More than likely it would be me that is confused when I try to play it back in a year or so and forgetting what I did.
Hmmm, so what was it I had for breakfast this morning?
Maybe others may suggest a better way, I know of none.