Hello, when I exit from Sonar X2, I no longer have windows sound. I have to reboot the computer to get it back.  I have "share drivers with other programs" enabled in the audio options within Sonar, and I am using ASIO.  My OS is Windows 10 professional x64.  I have power cycled my interface and it does nothing. 
 
My interface is an M-audio Fast Track Pro USB.  
 
Does anyone have any ideas on how to resolve this? I don't want to keep rebooting my machine every time I'm  finished recording. 

Hi. Have you tried to reinstall the drivers for your M-audio Fast Track Pro? If you did the Win 10 anniversary update, your drivers could have been overwritten. Others may know better. Hope it helps.
All the best.

I'm sure your aware of this from the support web page, I owned one and gave it to my son. Was terrible for me, would always cut out, so not surprised by your post.
 
 
Windows Releases (click on a version # to download that installer)

• 6.1.11
  • Jan 19. 2016
  • This is the final driver release for the Fast Track Pro
  • Qualified with Windows 7, 8, 8.1
  • Note that Windows 10 (or later) is not compatible and will not be qualified
  • Fixed noise or pops/clicks when streaming with Fast Track Pro's S/PDIF output enabled

I did reinstall the driver using 6.1.11.  So maybe the below procedure worked afterwards.. these options were not there after the Win 10 Anniversary update.. so thanks for pointing me in the right direction.
 
Turned out to be a windows 10 configuration issue within the playback properties. I unchecked the option under the advanced tab that says "allow programs to take exclusive control of this device" and I also checked in Sonar "share drivers with other programs"  
 
This seemed to work

KJS003333!!!! I OWE YOU BIG TIME!!!  I have been chasing a driver problem for a couple of years and your post turned the lightbulb on.
I have used Mixbus 3 for several years up until they released the newer versions. For some reason I could never get Mixbus 3 and Sonar Platinum to co-exist on the desktop while they worked fine on my laptop.
On the desktop, I could work as long as I wanted in Platinum but as soon as I used Mixbus 3, the drivers were gone from Platinum!! I would have to uninstall, go to windows update and let windows 10 find and re-install the drivers before Platinum would work again!!! What a mess.
Thanks to your post I realized that I had overlooked the unchecking of "allow programs to take exclusive control of this device"! THAT FIXED IT!!!
I can't tell you how thankful I am that the one line in your post has fixed 2 years of frustration over this. I can never repay you enough! I hope someday I will be able to offer you some help with a problem here to repay your kindness.
Thanks, again! Have a great life!!

Sidroe
KJS003333!!!! I OWE YOU BIG TIME!!!  I have been chasing a driver problem for a couple of years and your post turned the lightbulb on.
I have used Mixbus 3 for several years up until they released the newer versions. For some reason I could never get Mixbus 3 and Sonar Platinum to co-exist on the desktop while they worked fine on my laptop.
On the desktop, I could work as long as I wanted in Platinum but as soon as I used Mixbus 3, the drivers were gone from Platinum!! I would have to uninstall, go to windows update and let windows 10 find and re-install the drivers before Platinum would work again!!! What a mess.
Thanks to your post I realized that I had overlooked the unchecking of "allow programs to take exclusive control of this device"! THAT FIXED IT!!!
I can't tell you how thankful I am that the one line in your post has fixed 2 years of frustration over this. I can never repay you enough! I hope someday I will be able to offer you some help with a problem here to repay your kindness.
Thanks, again! Have a great life!!

No problem.  Glad I could help.

I had exactly this problem - all I did was buy a powered hub to plug the Maudio into ( amazon basics) and 6 months later the problem has not come back!