How did you create the document? When I hit backspace it does "turn into gibberish", but because it seems to inherit the type choices from the ether between the two lines to put it into Wingdings in red with italic and strikethrough. Did you create that type setting?
I ran into it while editing an interview text that had colors for people's names. It was surprisingly easy to reproduce, but creating the buggy documents got fixed at some point. The font and styles were altered slightly for dramatic effect.
