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