Okay, I have been trying to get a new Windows 7 PC up and running with Sonar and it has not been smooth.  I had been thinking it was weak audio interfaces (I replaced my old EMU 0404 that I used on my old XP system with a Tascam US200 and now on the Roland Quad Capture) but the audio continues to drop out with only moderate track intensity.  Simply put, my old (6 years?) XP system could process the same tracks without a hitch. 
 
I have spent many hours going over these forums over the last two weeks trying to find a solution.  No luck.
 
I have disabled onboard audio.  Using ASIO.  Networking off.  Samples on a separate drive. 
Latest Core i7, 8GB RAM.
 
Does anyone have a similar rig and use the Roland Quad Capture?  What setting work for you?  I have tried stretching the audio buffers up and down, turned read caching off and on, turned 'share drivers' and multiprocessing off and on, etc.  I feel like every rumor and hint that has appeared on these forums has been tried. 
 
Again it does not seem possible that it should be this hard.  Any hints?
 
 
 

Well, I really do not know unless something is amiss with your computer yet.
Have you used this program?
http://www.thesycon.de/deu/latency_check.shtml
Have you got graphics set on Performance?
Have you looked or searched for Optimizing Windows 7 (for perhaps running audio)?
After that since I am not using Roland audio/interface, I guess I would not know.
 

Can you post some screen shots of your Options>Audio settings?
http://forum.cakewalk.com/tm.aspx?m=2299538
Maybe we will see something amiss.
Are you running SHS 6 as Administrator?
Are you running it in Compatibility Mode?
Is the OS 32- or 64-bit?
Which version of SHS 6 did you load, the 32- or 64-bit?

Hi SpaceAlf and Greg, thanks for posting.  I'll check some of what you mentioned when I am back in front of my machine. 
 
What I know is that the OS is 64-bit Windows 7.  I have installed both 32- and 64-bit Sonar but am using the 32-bit because my plugins are 32-bit. 
 
I have some camera screen shots of my settings -- a little ugly because of the flash but this is all that I have on hand.  As mentioned above, I have spun the dials on many of these settings but this is what seemed to come closest to working reliably.  Note that some songs work fine but more 'busy' songs (with multiple audio and plug-in effects) dropout here but -- as said -- same tunes were okay on my old machine.
 
Super appreciate any ideas.

Okay, I made sure everything matched the suggestions posted above and I went through the ideas posted here:
http://forum.cakewalk.com/The-Sonar-x64Windows-7-x64-Install-Tweaks-amp-Compatibility-Thread-m1862515.aspx
 
Rebooted and -- magic! -- behaves well.  After working on a couple of different projects this morning, one of my projects crashed.  When I restarted, the audio engine would stop immediately, and would not cooperate.  Switching to the 'recover' version of the file made the audio engine behave again. 
 
So, no dropouts so far this morning (other than the crash) and no I feel like I can start doing creative stuff again instead of fighting tech issues.
 
Thanks again to those who chimed in.