Facebook Chat is now becoming more stable and consistent. The Facebook team made som improvement: Chat is now faster, more stable, and improved the technology on which it runs.
"In the coming weeks, we'll be making important improvements in the way connections are established and messages are sent, so that Chat will be much more stable for you and your friends. The biggest improvements come from changes that aren't supported on older web browsers. After evaluating the alternatives, we've decided to make rapid improvements and provide the best Chat experience possible, which means we'll no longer support IE6 from September 15th onwards," informs Facebook.