It usually means your system is not optimized for the high level of cpu use you are trying to run. Turn off read and write disk caching. When running many tracks, archive the tracks your not using. Plus there is an 8 age section in the Sonar help section that helps show you how to setup your machine for just this thing. Plus the new issue of Recording magazine has a good article on how to optimize XP (assuming that's what your using) for audio recording.