Responding to complaints from users, Facebook is promising to revamp its instant-messaging Chat feature, which has become one of the social-networking site's most popular.

"Many of you have told us that sometimes your Chat session comes and goes or even stops completely. We're working hard to end those interruptions so that your experience is stable and consistent," wrote Facebook software engineer Rodrigo Schmidt in an official blog post.

Work is already in progress to improve the stability and speed of Chat, which was launched about two years ago, and the enhancements will continue over the coming weeks until the IM experience is "hassle-free and uninterrupted", according to Schmidt.

Part of the problem is that Chat's popularity has grown significantly since its introduction, as has Facebook's overall user base, which now stands at more than 500 million active members.

Key changes depend on technology present on modern browsers, so Chat will no longer work on Microsoft's Internet Explorer 6 after Sept. 15 of this year, he wrote.