I just upgraded to Reason 4.0 from 3.5 and when I open and play any of the demo's or a very simple drum pattern that I created it chokes up. It continues to play but sounds like the computer can't keep up, sort of a skipping, choking sound. Wish I could describe it better! Any help would be appreciated. MacBook Pro, 2.2 GHz 2 gb ram OS 10.4.11

Also, I've experimented a lot with the latency settings so I don't think that's the issue. Thanks!

And did you try with a higher buffer size... try at 7200 samples and a sample rate of 44 100 just to see if it makes any difference.

I found the answer after poking around the Propellerhead forums! I turned off Airport and it works perfectly! Thanks for getting back to me. I didn't think it was a latency issue. BTW - This is my first post on the forum but I am a HUGE fan of the MacPro Videos! Thank you.

Cool! Thanks for posting the solution on the forum. It's always appreciated because other users could have the same problem.