Today I'm using Sonar for the first time in a few weeks.  Unfortunately, every few minutes the ASIO engine of my Focusrite Scarlett keeps stopping (cutting out).  When I start playback again, I just get crackle and silence.  The only way to get the sound working again is to restart Sonar.  Then, a few minutes later, it happens again.  And again.
 
I've never encountered this problem before.  The only thing I can think of is that I believe there was a Sonar update since I last used it (on 7 July). 
 
Is anyone else encountering a problem with the audio engine stopping/dropping out every few minutes?
 
 

First, make sure you have the latest Focusrite drivers and re-install them. Driver weirdness can happen with Windows updates, and there have been several lately.

I've been experiencing this a lot recently however I rarely update Windows now because it's good at screwing things up. It's food for thought though. To be more exact, just a lot of unwanted latency..occasional overloading of the outputs and crashing the ASIO driver. I work mainly in the box so don't have a lot of going on i/o wise. So I suspect the god of PC's is suggesting I upgrade.
 
 

Had a lot of issues with my Focusrite 18i20, so much so I gave up and returned it to the store. Turned out it was the 2nd time that unit had been returned. It was clearly an issue with the box being defective. It would just drop out for no reason, SONAR would lose connectivity with it as if I had unplugged the USB cable. Using it outside of SONAR it would cause stuck MIDI notes on soft synths. 
 
Not saying yours is defective but is the Scarlett sharing bandwith with any other USB devices on your system? Assuming it is USB, that can cause issues as well.

That's a good point.  I think a USB keyboard shares mine. Although that's not turned on all of the time these days.
 
 

And you probably know this, but USB interfaces should never go through a hub...a direct connection to the motherboard is necessary.

Tripecac
I've never encountered this problem before.  The only thing I can think of is that I believe there was a Sonar update since I last used it (on 7 July).

Sonar (via Command Center) doesn't update itself unless you manually run the update.  If you didn't do that, then more than likely it was an O.S. update that changed something.  Do you have Win 7 auto-update enabled? 
 
System Restore might be able to roll you back to before the last O.S. update.

Thanks for the info.  I restarted Windows, and re-installed the Focusrite drivers.   I'll see if that fixes things (next time I get a chance to use Sonar).

I know I say this quite a bit but...
Check your USB cable and more importantly, check your USB port.
I wore one out once and thought my interface (A Focusrite) was toasted because I had tried everything, reinstalling drivers, a new USB cable, turned out it was indeed my port.
 
It happens when you plug in/unplug the cable 20,000 times a year.
I've since set up a different manner to power/connect my gear (power conditioner= 1 buttons powers up all).

I don't think it's a hardware issue.  This is because I listen to music on the Scarlett all day long (Foobar, Windows Media Player, VLC, various games, etc.) and have been doing so ever since I got the Scarlett many months ago.  It's only when using Sonar (which is the only application I have which uses the ASIO driver) that I have encountered the problem.
 
Basically, after using Sonar a few minutes, the sound suddenly stops.  It's almost as if the ASIO driver (or the Sonar audio engine) "crashes", but there are no error messages.  When I try to restart playback, I just get crackle.  I also noticed once that there was CPU activity during the dropout, even if playback was stopped.  If I restart Sonar, the sound works again.... until a few minutes later, at which point the sound stops again.
 
Because the problem only arises when using Sonar (which is the only app I use which uses the Focusrite ASIO driver), the problem seems to be software rather than hardware. 
 
I can think of three possibilities:
 
a) The Focusrite ASIO driver is buggy and dropping out on its own (and Sonar is still working fine).
 
b) Sonar's audio engine is buggy and dropping out on its own (and the Focusrite ASIO driver is still working fine).
 
c) There is a conflict between Sonar and the ASIO driver; something is happening in Sonar which causes the ASIO driver to overload or crash (or vice versa), which results in a drop-out.
 
I could eliminate #a and #b by trying to use the ASIO driver and Sonar independently of each other.  I'd have to find another app which uses the ASIO driver (suggestions?), and then also test Sonar with something other than the ASIO driver.  I wish I could get Sonar to use the Focusrite's non-ASIO driver, but if I recall there was an issue with inputs; only the ASIO driver let me use all the channels on the Scarlett.
 
I've been using Sonar with the Scarlett for many months now.  I remember dropouts happening maybe once or twice before, but I don't remember ever having a consistent dropout like this.  So what changed?  Monthly Windows updates, and perhaps a Sonar update (though I'm not sure about that timing; was there a Sonar update after 7 July?)  I can't think of anything else, other than the fact that I'm working on a new project, using Drumlab for the first time.