In certain cases, such as when installing Focusrite software, the GateKeeper feature in Mountain Lion (Mac OS X 10.8) must be disabled. (Disclaimer: Be sure you know what you are doing before you disable a security feature such as GateKeeper! We are not responsible for any problems that may result!)
To turn off Gatekeeper:
System Preferences -> Security & Privacy -> General -> Allow applications downloaded from: Anywhere