(Sonar X3e)
Sorry, I used to know this one, but I can't figure out why, when highlighting, say, the hi hats in piano roll to be edited other random notes that I didn't select, like maybe the snares or something are getting highlighted, too? This causes me of course to have to manually deselect those notes that for some reason highlighted themselves. Why's it happening and how do I fix it? Thank you!

How are you highlighting them?

BRainbow
How are you highlighting them?

Where I'm seeing it happen is in Piano Roll view when I hold down the right mouse button then drag over and select some specific MIDI notes in, say, a drum groove, and in doing so, not always but often, some other notes nearby that I did not highlight end up highlighting themselves along w/ the notes I did highlight - and it's not that I accidentally highlighted them, because sometimes the self-highlighted notes are down at the bottom like a kick drum whereas I'm trying to highlight/edit hi hats that are further up. I'm just getting back into Sonar after some down time and I remember this problem from before and don't fully recall if I sorted it out or not. I believe this happens when trying to highlight MIDI notes that are part of a copied MIDI clip, but I'm not sure why that would matter here. Thanks

Weird.  Never had this problem.  Sorry I don't have an answer.  Two thoughts:
1.  Mouse battery?
2.  Bounce to clips first so its all one clip before editing in PRV?
 
Good luck.

But thanks anyway man. Yeah I thought maybe it was a bounce to clips issue so I tried that and still the same problem. Anyway installing SPLAT for the first time now and wil see if it does it there.