When adding / editing a user in chrome the username / password boxes become yellow when you have a saved password in Chrome for the website. This is not usefull when adding another user.
/admin/content/new?type=person (with "Enable login" field)
/admin/content/34xcvfskdjasrt789j34r78j34qjfds (relation with "Enable login" field)
Turn off autocomplete for this form (or form fields) http://stackoverflow.com/questions/175951/how-do-i-stop-chrome-from-yellowing-my-sites-input-boxes