Sound/Audio issue when Sonar is running

Because Sonar takes exclusive control of your device. You can try changing this behavior in Sonar preferences but it's possible that your device driver doesn't support multiple clients.

Exclusive control means that ONLY Sonar gets access. So no, those other applications won't be able to access your soundcard at all.

Sorry to hear about total paralysis!
In addition to deselecting the "exclusive" setting in Sonar (as others have said) it might be worth going to Windows Device and Printers and right-clicking on your Duo Capture and choosing "sound settings". Make sure that the Duo Capture is set as the default device for Playback, then choose Properties - Advanced and de-select "... exclusive control ..." there too. Probably also worth doing the same for Record.
 
 

It's a little unclear to me what you mean by " other programs not being played". I guess you mean they're silent but running.
Usually that is solved by clicking "Share drivers with other programs" in Sonars Options.

You might try changing to WDM driver mode in preferences if your interface supports it. ASIO drivers bypass the Windows audio stack, WDM does not so sharing audio resources is likely to be easier.

I run Windows sounds through my onboard Realtek (set to default) and only use my interface for programs I allow. Disadvantage is this requires two speaker sets, but works well.

ASIO drivers are only as good as the programmer who wrote them. Not all will allow multiple programs to access the driver at the same time; and if they do, they need to be at the same sample rate/bit depth. That is another thing to check that Windows sound card settings match what SONAR has them "locked to." If they do not match, multiple programs will have issues accessing them at the same time. If they do match, the ASIO drivers may be limiting you, so WDM mode would be worth trying.

WDM mode is not "bad," per se, and if written properly should not be an issue with playback scenarios (due to potentially higher latency).

frkfir
Well, I'm trying to change drivers to WDM mode and everything gets messy.
The software did test on my computer If this driver is appropriate for my computer and it is appropriate.
But any sound that I played from Sonar, came out with dirt.

 
Many interface drivers focus on ASIO and not so much on their WDM drivers, so your mileage may vary there. You can also try WASAPI driver mode. One thing you could try is increasing the number of samples on the Driver Settings tab in Edit->Preferences after you selecting either the WDM/KS or WASAPI driver modes. This will increase latency which may be a problem if you monitor your playing/singing through Sonar while recording, but if you're mostly concerned with mixing it's not an issue and may resolve the "dirt" issue.
 

frkfir
Once again, and I can't hear any sound from any other source or software when the Sonar software is open.

 
Just to reiterate another suggestion, make sure that the "Share Drivers With Other Programs" checkbox on the Playback and Recording tab in Edit->Preferences is checked.
 
Good luck!