I kind of skimmed the last handful of posts in this thread - and DID read the first bunch thoroughly, and have a question.
 
For the folks who also experienced this issue, as well as the original poster of this thread, is it possible you had Windows also using the audio interface as the Windows Default Audio Device?  If yes, then I would suggest that might explain some of the issues - as the ASIO specifications are written to only allow a single application to have control of a set of ASIO drivers. 
 
So, if both Windows (playing of Windows sounds - mouse click, any of those dings/bells/whatever sounds that Windows plays - as well as Windows Media Player, playing a video on YouTube, etc.), AND Sonar are set to use the ASIO drivers of the audio interface, then there is a good chance of conflict.
 
I have been rock steady for years now, since I learned to split sounds off - I have Windows Default Audio Device set to use either a set of computer speakers, or the HDMI HD audio of the HDTV I use for my computer's display monitor, and it is ONLY Sonar that is set to use the ASIO drivers of my audio interface - and I NEVER have those weird conflicts like what some folks reported in this thread.
 
I recommend that you try testing setting the Windows Default Audio Device to something OTHER than the audio interface, and THEN see if Sonar works properly being the only application up and running pointing to the ASIO drivers of the audio interface.
 
(I do also have other music applications set to use the ASIO drivers of the interface, such as the stand-alone versions of Dimension Pro, Rapture, Rapture Pro, Kontakt, etc.), BUT I would only ever be running one of those programs in stand-alone mode at a time, and never also try to have Sonar up at the same time).
 
I hope the above makes sense - it is easy to test out, and if I didn't make enough sense, please let me know, and I will take another shot at explaining the above to make it clearer. :)
 
Bob Bone
 

+1
 

Shambler
I get this with my Quad Capture, a reboot always fixes it.

I had this problem right after I installed "Razer Synapse" and "Razer Cortex".
Razer Synapse is an app for customizing my Razer gaming keyboard
Razer Cortex is a game boosting app.
Uninstalled both, restarted, and I have my Asio drivers back.
What's funny is I did this to myself a year ago, and forgot about it and reinstalled both recently. Took me a day to have a flashback and immediately solve the problem again.
 
 

Had the same problem with 2 Studio-Captures synced in ASIO. Clicking restart has always fixed it. Rebooting would never bring back the ASIO drivers. Funny, the other drivers still worked. Just the ASIO would disconnect.

Rare on my Studio Capture but a reboot ( occasionally TWO reboots) fixes it. For good luck  connect to the internet before turning on the Roland - then give it a few minutes to think after you turn it on. It is my understanding that the Roland checks for drivers/updates on startup when internet is available. 

Fast solution how fix card without reboot PC
https://www.youtube.com/w...c&feature=youtu.be

Never had that problem with my Octa-Capture and Win 10 (early versions as I sold the Octa-Capture when I upgraded to MOTU).  

I don't know this for a fact (so take it for what it is), but I don't think Roland has updated the Quad Capture drivers in quite a while.  When I had one I experienced the same problems as others on this page.

If the Quad capture is now class compliant in Win 10 it doesn't need new drivers for Win 10. Don't know about earlier OS's

Looks like the OP has gone leaving a thread title that creates an impression there's this big problem with Sonar when his problem has nothing to do with Sonar at all.

Then another poster says when they read the title of the threads they're too scared to update Sonar because of all the problems.

mudgel
If the Quad capture is now class compliant in Win 10 it doesn't need new drivers for Win 10. Don't know about earlier OS's

Looks like the OP has gone leaving a thread title that creates an impression there's this big problem with Sonar when his problem has nothing to do with Sonar at all.

Then another poster says when they read the title of the threads they're too scared to update Sonar because of all the problems.

Mudgel:
Thanks for the clarification on the driver issue. 
Plus, you make a great point about blaming SONAR when it's not the problem to begin with.  I know I've done it myself.  There's a good moral here, which is get your facts together before you start casting aspersions.