Try starting aMule through the terminal using the following instructions:
* Control-click on the aMule application icon in the Finder and select 'Show Package Contents'.
* Navigate to Contents/MacOS where you should see the file 'amule'.
* Open Applications -> Utilities -> Terminal.
* Drag the amule file from the Finder and drop it in the Terminal window. Terminal will insert the path to the application onto the command line.
* Hit return to start aMule.
* aMule will then produce some output in the terminal window. Copy that output and post it here on the forums.