This afternoon, the file for Learn mode get mysteriously wiped. I've restored it from my code repository and it should function fine now. I'm looking into the cause of this problem, and if you notice any other issues, post them here. I was making some small updates to Quizlet today, and some saving problem must have arisen. Thank you to the people who reported this problem.
While I'm here, I might as well give a quick update on Scatter. I've built it to work outside of Quizlet (as well as inside it), so you will be able to embed it in your own site as a sort of widget. I've been testing it on some other sites, and it works beautifully. I'm really looking forward to releasing it! Today I also completed the automatic saving of "Ignore" and "Prompt" preferences. These features will be released in the next major upgrade of Quizlet.
Even more tangential, I upgraded this blog to Wordpress 2.1 today. It's a great update, I highly recommend it if you use WP for your blog.