Seriously? Emulators themselves are not wares, and you technically CAN rip your own carts with the right equipment...
Anyway, you weren't very specific so I can only give generic app troubleshooting advice:
1. Check ~/Library/ and ~/Library/Application Support for any files that clearly belong to Snes9x, try moving them to your desktop temporarily and launching it again, see if it's corrupted preferences/the like.
2. Try opening /Applications/Utilities/Terminal.app and invoking Snes9x from there (<path_to_Snes9x.app>/Contents/MacOS/<executablename>(most likely snes9x, though I personally don't know)), and then see what the command-line output is, then copy & paste it here so we can see.