Some sort of find the center line assist tool lol?  I got this today during a flight.  I couldn't seem to get rid of it (I didn't try reloading as it was mid-flight and I was using FSPassengers.  Anyone else seen this?  Know how to get rid of it?

 

That is a display artifact, try adjusting your display settings for the JS41 and/or video.  Some seem bothered by these more than others, sorry that's about the extent of my knowledge.

I know some users have issues with their graphics card not supporting the cockpit windscreen icing effects, which causes random flickering. The fix for that was to set Virtual Cockpit Model Optiosn to Medium in the Jetstream 41 Configuration Manager. Perhaps you could try that and see if it fixes your issue?
 

I already turned of DX11 preview (or 10 or whatever it is) in the FSX menu because when it is on the runways look like they are having seizures lol.  I will turn the icing off as well, thanks!