Hi all,
 
I am running SONAR Home Studio 6, and when I playback audio the audio engine stops.
 
I am using version SONAR Home Studio 6.2.2.
My sound card is a Sound Blaster 5.1 VX.
I am using WDM/KS drivers, which are the only ones that work.
I am using a USB audio device for the recording source (my mixer)
I have tried maxing the latency.
 
Does anyone know what might be causing this?
 
I am wondering if its using the USB device as the record timing master that may be causing this, but this is happening during playback, not recording.
 
Is there any debugging console or anything?
 
The sound comes through (and eventually starts staticing which I have to reset the input echo to clear it), but its only when I playback when the audio engine stops.

Does that USB mixer also act as audio interface, as it seems to me?
If you are using both the SoundBlaster and the mixer simultaneusly as interfaces, I recommend using only one of them as the first step of problem solving.
 
Has everything worked ok earlier? What are your PC specs? Are you using heavy VSTs?

Is this a Behringer USB mixer per chance? 
Sonar/Cakewalk software is very picky about using audio drivers. Most of the lower priced USB mixers will not perform well with Cakewalk because they do not write proper ASIO drivers for the device. Sound Blaster cards are super bad for this as well. So you have on hand 2 audio devices  that are not recommended for use with Cakewalk software. 
Either look into purchasing a proper audio interface or try Cubase, Reaper or ? 
 
I would recommend a proper interface as that is the most important part of working with any DAW system. You can get a pretty good interface for $150 these days. The Scarlett 2i2 as example.