Greetings:
When I set the ASIO latency on Sonar (latest version) to 512 - I get continuous pops and crackles.  When I lower the latency to 256, I have this happen on rare occasions.  I thought it should be the other way around?  Increase latency on playback and less issues.
 
I may have a clocking problem as I look into this.  
 
Best,
AB

Might help if you post what audio interface you are using.  

Lynx Aurora into Lynx AES16e