In Popularity Lists Widget configuration menu, if I:
1. Place some text with double quotes (") in "Before list is placed:" (e.g. <div class="popular_posts_text">)
2. Save Changes
3. Reopen the same widget configuration box.
Then the configuration data gets messed up. I think you need to take care of double quotes (") escaping. Current work around is to use a single quote (') instead of double quote (").