Using Windows 10 home...  I'll watch a YouTube or something... Windows Media player, I guess.  Works..  then sometimes I get an error...that the video won't play back.
I go open Sonar, play a short section of a song...any song.  Then back to watching vids... They play just fine!
Same when I use my Sony Video editing.  The final render sometimes won't play..   same solution...open Sonar and play a little snippet of something, and I'm good.
 
Wonder what's up??
 
and another issue... Track view seems to freak out my audio card sometimes with a RF type interference sound.  I can then jump my sample rate way high...it goes away.  Down to 64 samples, it's the loudest.  BUT...when I open a plug or ANYTHING on top of the track view window, the sound goes away?? 
part 2...wonder what's up with that too??

Pretty much the same thing is happening to me. If I am working on a project in SPlat, I can't watch YouTube videos or play tracks on Soundcloud, etc. Sonar is taking over some process that won't allow anything like that to run. Even if I exit out of Sonar the problem persists. I have to restart my browser in order to be able to watch videos or listen to audio online!

Try enabling/disabling the Share Drivers setting:
https://www.cakewalk.com/Documentation?product=SONAR&language=3&help=Dialogs2.053.html
 

Previously done without success. Thx tbough! !