After encountering this problem myself and seeing others with it on the Steam Community, I did some digging and found a solution to the "Bad Mojo CD Not Present" error. I've put this solution on the Steam Community forum for Bad Mojo and figured I would put it here, too, seeing as it's apparently a very common issue. Here is the solution that worked for me:

"I've fixed the problem! Go to C:\Windows\ and delete the file "badmojo.INI." Then go to Bad Mojo's directory (probably ["C:\GOG Games\Bad Mojo\"]) and copy the BADMOJO.ini from there into C:\Windows\. That did it for me, and I hope it helps you guys!

Source: [removed because GOG won't let me post links]"

I hope this helps!

EDIT: Changed the path from what I assumed Steam uses to the default GOG path.