Reply to Ableton Live 8 Audio Engine not working with Core audio Mac 10.7.5

Just downloaded the above as a trial, when I go to set the Audio in Preferences, I select coreaudio etc, but Ableton still shows a big exclamation mark, and the engine won't turn on so no sound.

I have a very recent Mac & all updates. Also tried reinstalling, same problem.

This is really p*ssing me off.

Can anyone help???