When recording a soft synth track like true pianos or strings, i get these vertical lines down the page of the clips. Doesn't seem to disrupt the recording. I can do the take ok. I even get a pop or two here and there. Strange... any suggestions?

Under view>display>vertical grid lines is where you can turn this off.  I'm talking about the view tab next to options.

I've seen something similar, and it's not the optional grid lines. For me it's happened when I'm recording a soft synth and I change anything on the screen ( zoom level or similar). It's a graphical remnant/glitch and usually goes away once transport stops and screen is refreshed. I've seen it a few times and it's been random in my case.
 
Can't offer any fixes, but I've def seen something similar.