When you try to import the Sms_def.mof file to customize your hardware inventory in Microsoft System Center 2012 Configuration Manager, the file does not open. Additionally, you receive an error message that states that the file contains invalid data.
To resolve this problem, check the integrity of your MOF file. To do this, open a Command Prompt window, type the following command in the directory in which you last saved your MOF file, and then press Enter:
mofcomp.exe -check YourMOFName.mof
For more information about how to test your MOF file, visit the following Microsoft TechNet website: