For a few days I have been puzzling as to why certain VSTIs are suddenly dropping in volume and spurious expression values appear in my MIDI tracks.
 
 
It was a rather obvious culprit that I over looked. The expression pedal attached to my NI S61 keyboard was in the half way position. I think a vibration or something was causing it to move very slightly and generate a value. I have it hard down now and the problems seem to have gone away!
 
Nothing to do with Win 10 updates at all it would seem!

Been there. I did that with my volume pedal and my Axe FX at the same time I did firmware update. Posted on their forum thinking the firmware update did it and a kind mod suggested the fix.
 
Almost did it again last week but remembered!
 
DOH! :)

Good catch !  
I had a similar problem where a noisy slider on my Roland keyboard was generating volume changes. I finally found it by looking at MIDI messages and noticed floods of a certain CC value. It did drive me crazy for a bit though because it was intermittent.

I'd be embarrassed to say how many times this exact thing has happened to me, usually during setup at a gig. For how many times I've run around checking cables and mixer settings because the Hammond isn't making any sound you'd think by now the swell pedal would be the first thing I'd check!