Yes the "Your CD key is invalid or being used by another player" thing happened to me to. This usually occurs if you got the CD Key off the internet or borrowed the disk from a friend and used their CD Key. As for the lag thingy, the only thing I can think of is if you borrowed someone's disk and upon giving the disk back ran the game through Republic Commando>Game Data>System>Republic Commando exe (Which is how you play without the disk, but this tends to create some lag.) Other than that, no idea. Welcome to LF by the way Ubermensch.