Mike, at least I now know my machine is not the only one exhibiting this behavior! 

Overall I believe it is a combination of memory intensive FX/plugins and a load going on in each track just creating a bottle neck 

Along the lines of what Robert and Charlie are getting at

baudze


One more piece of information: The dropout occurs at the same point in the song even if I solo a single track (any track, including a blank one). Quite strange...

Just for your information, tracks that are muted (or "not soloed") are still processed by Sonar as if they were playing.
 
This is done so that you can mute/solo tracks whilst playing back and they will start immediately without issues.
 
Hence your dropouts even if guilty track was not playing.

baudze


Mike, at least I now know my machine is not the only one exhibiting this behavior! 

Im sure many have experienced it,  I fell onto it cleaning up bleed on drum tracks when I got bored and decided to split Beats into Clips along with the FX I had running on all the tracks. 


This is when I decided to go to the Audio to Midi track conversions on my Live recordings for Drums. 


If I remember right, the Control Bar on Console View didnt indicate any problems as far as CPU load, Memory Usage, and Load on the HDD. Everything looked good but Sonar would just "STOP" dead in a certain spot everytime I hit play.  Usually would make it to like the 2 minute mark.


Im kinda watching to see if its cleared up in X2,  but then I dont work with tracks like that now so no big deal.  

I finally have a definitive answer to what was causing my heart-ache. After much research and the use of several tools (DPC Latency, LatencyMon and finally Microsoft's RATTV3), I zeroed in on iastore.sys - an Intel driver for their RAID management software called "Intel Matrix Storage Manager". This awful tool does not cause persistent latency (which is why the problem never shows up as a spike in DPC Latency). Instead, it does intermittent but invasive hard-disk polling at some frequency - not invasive enough to cause a latency spike, but invasive enough to disrupt Sonar's audio engine - hence my consistent dropouts. I simply uninstalled the Intel driver (I'm not using raid anymore) and all my problems have gone away. 4 hours of music-making so far (both new and old projects) and not a single dropout since!

I hope this helps someone else in the future.

Glad you fixed it. I've never been tempted to use RAID on my DAW computer because I always believed it added unnecessary overhead. Good for you for sticking with it and finding the culprit. A lot of people would have just blamed it on Sonar. 

Man, I can only aspire to be as smart as some of you guys. This thread is hardcore.

This thread makes me proud to be a member of this forum. And a very happy new year to the OP. Well done indeed.