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 files without dropouts.  The new system's hardware is superior in every way.
 
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, 7200 RPM HDDs.  I've watched the task manager/processes and nothing other than Sonar is busy.  
 
Does anyone have a similar rig and use the Roland Quad Capture?  What settings 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.  It does not seem possible that it should be this hard.  The new system does load samples/patches much faster, so I do see some benefit.  
 
(I reposted this from the Home Studio forum because that forum is largely drying up.  I assume that the settings that work for 'regular' Sonar will also work for HS6XL.)

There's gotta be an answer somewhere. I also have just recently purchased a Quad-Capture Interface, but the audio clicks and cuts out before stopping completely. It has to be a driver issue since it works fine on other computers that I tested it on but I can't figure out which one yet. Otherwise I have no idea..

This remains a problem for me -- audio engine stops on a regular basis.  Sometimes even every time I stop playback..  Can someone at Cakewalk hep me out?  Been suffering from this for two years almost.

If you want a dialog with Cakewalk, you need to contact them directly http://forum.cakewalk.com/FindPost/2090582
 
The fix may be as simple as increasing the DropoutMsec in Cakewalk.ini http://www.cakewalk.com/Documentation?product=SONAR%20X3&language=3&help=INI_Files.6.html#1134652 to 500 or 750.

Ignore the left side of this image, as I made it for another issue, but the right side shows my settings.
Have you tried running LatencyMon a free download that should help analyse your system for issues. If it says their are some, then I beleive it indicates you Soundcard is not the root of evil. There was a thread recently where someone asked about how to interpret LatencyMon, so maybe start a thread with the results and get assistance if it's saying there is an issue with your system
 

Latest driver and system program installed?
My Quad-Capture has been working fine on my system (with the following settings).
 

Thanks Sooooo much!  Tak T., my settings were already similar to yours so I changed it to Kamikaze's -- and it seems to have fixed it!  Inserting the screen shot made it so easy to see what to fix.
 
Thank you again!
 
cw