Data transmission is not stable, failed to send player to server

I play crossfire about evey week,the only changes to my computer know is that I downloaded ati catalyst. Every time I boot up the game it works normally, till I log in. Then an error message pops up and says "data transmission is not stable,failed to send player to server, please try again. I did try again but the same thing happens all the time. There is nothing wrong with my internet connection.