Port conflict with max/msp

Hello.

I am trying to communicate arduino with max/msp. Just sending the pin number the message is sent from.

I am using the SimpleMessageSystem library. I did it many times, but i don't know what happen now with the arduino diecimila. When i launch max and set up the right port, arduino just quit and stop working....

So i quit max, re-plug my arduino and launch max but he same thing happen. It's like there is a port conflict between both of them.

Any Idea, where does this can come from?

Thank you