This may not be of any use to anyone else but my life with Sonar just took a magnum leap forward by a simple step.  At least I THINK this single step solved my problems.
 
My first keyboard controller was an Edirol PCR-M50.  Roland and Cakewalk were tight; all should be good, right?  And it used to be.
 
Starting with Sonar X1, I think, my installations became arduous nightmares and Sonar became unstable.  I switched to Live as my primary DAW around then, too, and it is rock solid.
 
But I keep upgrading Sonar and I was almost ready to throw in the towel during my X3 installation process.  I downloaded all my installation files three different times, I turned off every background service I could think of that might interfere - I don't have virus protection on my DAW and only Windows Defender is there, which I turned off as much as possible - and I still saw way too many white screens with "Sonar has quite working" messages. This cost days of frustration and wasted time.
 
In the problem "details" I would frequently, though not always, see references to the Edirol dll as a problem area. So I moved it out of Sonar's scan list and suddenly X3, X2 & X1 all seem rock solid! 
 
So, if you are having problems with Sonar there may be something very simple getting in the way and the "details" part of your crash may give you the answer.
 
If you've read this far, I am curious, however, HOW could an old or bad dll for a keyboard controller wreak such havoc?
 
Maybe I did something else that solved my problem and the Edirol dll relocating was a coincidental, but actually unrelated, event and I am errantly attributing Sonar's new stability to getting this dll out of Sonar's scan list.
 
Comments?
 
 
 

I too Have stabilty issues with X3c .For instances today I have had more crashes Eq-ing vocals than I CAN REMEMBER !! Nothing specific as in the same Plug-in etc but silly small things such as  volume clipping an Audio Stem and "Bam -crash !"  with not even a Report Pop up to send ! I very rarely complain ( been with Sonar since 7 ) and I have all the notifications from this forum sent to my Samsung mini S4 as this site is great for little "snippets " of info if I can't figure something out myself but.......  wow !!!!! Yesterday I didn't fair much better- I had my Vocalist partner in crime to record new material for our label and as soon as i connected the mike to my Edirol UA-4FX all sorts of weird and bizzare  Issues -such as the mouse would not right click then  X3 would just " hang " ( the White Screen !!) and wouldn't close ;to name only one issue yesterday. To say I am scratching my head trying to figure -How,Why,What- is an under statement .I too went with Ableton as IT IS ROCK SOLID plus the ins and outs for Synths are way way way easier than Sonar . However Sonar is in my blood for ease of use (when functioning!!). Pundits say Possession Is King in Football well so is STABILITY IN A DAW especially when It earns the Dollars  

Hmmm...post 1 says "Sonar unstable, Edirol driver, removed driver, Sonar stable." Post 2 says "Sonar unstable, Edirol driver." Maybe try removing the driver...
 
It's really not that weird a driver issue would cause havoc with a program; the core of a DAW is its audio engine, and if a driver messes with that, expect problems. Newer versions of programs are often in sync with newer drivers for an interface but out of sync with older drivers.
 

Any software that is close to hardware can cause trouble, that's why apps stay well away in their own protected layer. It is up to the operating system to manage dodgy drivers not sonar. Sonar often ends up being the messenger for these type of scenarios(dodgy drivers, dodgy firmware), and the victim...
Don't get me started on plugins.
 

CakeAlexS
Don't get me started on plugins.

Believe me, I won't. Because then I would get started on plug-ins.
 
I have to say one of the cool things about the ProChannel modules is that I know they won't give Sonar any problems. Or me, for that matter