Ghosting happens when you are disconnected from chat but your nickname does not immediately leave the room. When you try to rejoin the room in that instance it will change your nickname by adding numbers to the end. This is because you can not enter a room that has a user with the same nickname. Even if it is your own. Your "Ghosting" nick should leave on it's own shortly.
If you have been kicked for "Ghosting" then you should simply click the browsers refresh button (usually found on the left side of the address bar). This is usually done so that you can go back to using your normal nickname.
If you constantly have ghosting issues. Some of the following corrective measures might help.