Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
It seems many people have had this issue (and i've heard reports that it has to do with using Firefox). Try using another browser or going on the afd version of PS http://showdown-afd.psim.us/. Many people have had more success getting on this