I just recently noticed that disabling "Low Latency Mode" on the ASIO driver for my Roland Octa-Capture has made the Sonar Platinum (Dorchester) audio engine more stable.  As such, I'm posting this so that it might help someone else that has a similar setup and is experiencing the same symptoms.
 
More details follow:
 
It used to be that when I would manipulate the frequency handles of the ProChannel QuadCurve Equalizer fly-out panel (in all versions of Sonar that have had that feature), my audio would frequently drop out and I'd have to restart the audio engine.  (That was the only operation that seemed to cause audio dropouts on my system, so it wasn't a big deal.)  Since disabling "Low Latency Mode" in the driver for the Roland Octa-Capture, the audio engine no longer drops out when manipulating those frequency handles.
 
The only downside is that it added 2.1 milliseconds to the reported "Total Round Trip Latency" which brings me up to 8.1 milliseconds.  Still acceptable for me.
 
I'm running the latest Octa-Capature drivers.  My system is a 4th Gen I7 with 8 GB of memory running Windows 7 Pro - SP1 (64bit).  I run Sonar Platinum (Dorchester) 64-bit.  All of my projects are utilizing ASIO at a rate of 48khz with a bit depth of 24bits.
 
Hope this helps someone out,
Paul

Thanks for the post kellerpj.    I have had this happen a couple of times with my octa capture and will try this out.

Dropouts and crackles that occur when manipulating a screen element can sometimes be caused by graphics issues.

Some things to check: graphics card drivers update, settings that provide advanced graphic features which aren't necessary for Sonar.

FCCfirstclass:
 
No problem.  When you try it, let us know if it works for you as it is seeming to work for me.
 
Thanks,
Paul

Mike:
 
Thanks for pointing that out.  I try to keep things as up-to-date as possible.
 
Most likely it's due to the synergistic effect between the graphics drivers and the Octa-Capture driver.  It seems that changing settings in the Octa-Capture driver mitigated the (only) issue I've had with Sonar's audio engine while allowing me to keep all the features of the graphics subsystem that came with my system.  The settings change does increase the latency, but the increased latency is still acceptable for me.
 
Later,
Paul

Just an update.

Since Gloucester, I've been able to turn on "Low Latency Mode" on the Octa-Capture driver and the audio engine no longer drops out when manipulating the frequency handles of the ProChannel QuadCurve Equalizer fly-out panel.

Also, when "Low Latency Mode" is enabled, my Total Round Trip Latency is now lower than it's ever been at 4.6 ms.

Must be that amniotic fluid they put in the Gloucester audio engine. 8?)

Later,
Paul

All "low latency mode" does, I believe, is use slightly smaller buffers therefore, slightly lower latency, therefore it's more likely to cause dropouts. The Edirol/Cakewalk/Roland UA-101 had the same driver setting.

I had the EQ zippering problem in X1 using a Ua-101 unless I used WASAPI drivers rather than ASIO. One of the Sonar updates, or maybe releases, eventually solved the problem I think.