Based on A.I. research, cod4x_xxx.dll is a file used by the Call of Duty 4: Modern Warfare video game. The xxx in the filename represents the version number of the file.
If you encounter errors related to this file, it may be due to issues with the Call of Duty 4 game installation or with the file itself. You can try verifying the game files through the game launcher or reinstalling the game to see if that resolves the issue.
The cod4x_xxx.dll file is not created by Microsoft Corporation, nor is it related to Microsoft Visual Studio 2010 or the Microsoft C Runtime Library.