Just bought the game today for my PC. when i try to join a session that is in play, i get the error that my key is already in use. i can jump on empty servers np. Did i do something wrong?

You need to enter your serial number on the LOGIN screen, where you put in your username and password, on the bottom there is a spot for "enter serial number" or something, very bottom.. then it will work!

TY will try that out. This is the most responsive community i have been on.

Worked like a boss. TY