When I join a multiplayer game it says "CD Key invalid or in use by another player".

I'm like... WTF?! I just bought this game yesterday so no one else can have my CD Key... and it let me install with it so it can't be invalid.

Could be the server you're trying to join is using warez, and that's why it's not recognizing it.

Keep trying other servers and see if you still have the same problem. Perhaps you need to reinstall your game, re-entering the CD key from printed on the cd booklet/manual.

I'm afraid the CD Key thing is a controversial topic (due to people abusing the information) here on the forums relating to warez.

So please send your questions to Lucas Arts Technical Support, not us.

If you need to keep posting on here we may ask you to prove you own the game (through scans, pictures of receipt, etc).

Do NOT post your CD key here or give it out. Nobody but LucasArts can give you a new one.

The only other suggestion I can think of is that you might wish to disable Gravis Xperience software when you are playing, if you have it installed anywhere on your system, and try joining servers with the lowest ping possible.

Good luck!