http://community.callofduty.com/message/413513938

ATVIAssist     2012-11-13 11:21 (in response to Echojaybird)

Hey guys,

We sincerely apologize for the issue that some of you are having with installing Call of Duty Black Ops II on your PC because of you received a copy of Mass Effect 2 instead of Disk 2 of Call of Duty Black Ops II. Rest assured that are teams are investigating trying to find out what cause this to happen.

We do need some of your help in order to find out what's going on. If purchased Call of Duty Black Ops II and you did receive a copy of Mass Effect 2 with your physical copy of the game, let us know where you purchased the game from. When you purchased the game and if you can provide a city and state to where you purchased the game from. This will help us go a long way to find out what's going on.

We know that you want to play the game as soon as possible and luckily you can. First, you would need to make sure to have a Steam account. If you have not yet made a Steam account, visit http://store.steampowered.com/about/ to download the app and create an account. Once you've created an account, you will nee to use the product key that you were provided in your game case in order to activate the product on Steam. You can find the instructions here https://support.steampowered.com/kb_article.php?ref=5414-TFBN-1352

Please follow these instructions to activate a new retail purchase on Steam:

1. Launch Steam and log into your Steam account. 
2. Click the Games Menu. 
3. Choose Activate a Product on Steam... 
4. Follow the onscreen instructions to complete the process.

Once again, we sincerly apologize for the issue but we are investigating it to the fullest extent. If we get any new updates, we'll make sure to post it here and also on our support site at support.activision.com.  We thank you for understanding and if you need further help regarding this issue, feel free to update this thread. ^MM