Thank you for replying,  I have found the solution to my game crashes!
In the Compatebility tab of my CoD install I checked Disable fullscreen optimizations and set compat. mode for Windows 7.
I will update this thread if I run into more trouble.

I'm working on a custom map. When I launch it using Launcher the map runs fine, but when I try to start it in-game my Cod crashes. On my brothers install the game returns to the main menu. If anyone could shed some light on the matter it would be really helpful. If you need error logs ...