This has been bugging me for a while.. when I click & drag on a style dial while playing a track there's a short delay, like the CPU catching up (there's no audio dropout, just a very short visual delay) . Then my mouse cursor disappears and doesn't come back. In other Windows programs it's still there. But I have to restart Sonar to get it back in Sonar.
 
I got Sonar Pro on Windows 7 64bit, now using an M-Audio 44.

What graphic card are you using and are you using the latest drivers from that card's manufacturers website?

Is it a logitek mouse ?

GTX 1080, latest drivers, Logitech G602

occide
GTX 1080, latest drivers, Logitech G602

Try a different mouse. (as a test)

Don't have one right now, but I will. Maybe a VNC connection with mouse emulation will do.
 
But I noticed it only happens when the style dial is initially deactivated. Turning the knob also turns on the style dial. While turning Sonar hides the mouse, this is the normal behaviour. It's just not normal that it won't come back.

This has happened to me many times in MC7 also if I used those dials.(i don't really need them now I have plenty of plugs instead).....I always ended up having to reboot MC7.....I don't use a mouse.....it's a laptop with touch pad/cursor. gotta be a bug cause everything else is very stable.