The issue you are describing points to inadeuqate system resources, CPU must be 2.0GHz or faster per core (in multi-core systems), older and/or single CPU systems may not have enough co-processing power to handle the real-time audio operations, make sure not to use a hard drive that is too slow. Make sure you are using a dedicated internal 2nd audio drive of 7200 RPM or faster, or an SSD. If you're on a laptop, make sure to use a 1394 external enclosure with a 7200 RPM or faster drive in it, using the main drive (same one your operating system and programs are installed on) will give poor performance. Make sure your system has enough memory to operate. By todays standards 8GB is minimum recommended for stable performance with modern DAWs such as Studio One.