Sometimes the error is triggered by Windows attempting to launch the game through a broken shortcut or the Steam bootstrapper rather than the executable itself.

Ensure your Steam language settings match the files installed. Some users fix this by switching Steam's game language to English, allowing it to download the missing "zone" files, and then switching back. 2. Verify Game Integrity (Steam Users)

Double-click BlackOps.exe directly from this folder instead of using a desktop shortcut. 4. Compatibility and Administrator Settings