If you encounter error code 0xC004F074 when activating your Windows 7/8 Enterprise, it may due to the Date Time/Regional settings are not matching (If the difference between system time on the client computer and the system time on the KMS host is more than 4 hours).

Please correct the Date, Time and Region (Time Zone) and try to activate again.References: When trying to activate you get 0xC004F074 with description The Key Management Server (KMS) is unavailable