CPU Overloads and Timeouts during Audio Mixdown

This has been going on for a year. I see many, many posts so there must be a problem. I’m running Cubase 6.0.7 with Snow Leopard with 4G or Ram on an Intel Mac Pro core duo. I wish Steinberg would be proactive with this. When this happens I am ONLY running Cubase and my CPU activity is about 3 to 10%; not enough to bog down Cubase.