Have you tried to reset Safari? (Safari > Reset Safari)
Or tested anything else ... ?
You could try in Safari ... File > Export Bookmarks > export to e.g. desktop.
Then quit safari, go to [home folder] / Library / Safari and remove Bookmarks.plist file, take that for example to your Desktop.
Then restart safari .. it should start without your bookmarks - in which case you could try to select File > Import Bookmarks, and select the one you had created earlier.
That could work if it's something in the bookmarks file being corrupted.