About once out of five sim startups I experience very strange mouse control and I cannot figure out what it means or how to change it.  It is not repeatable.  If I shut down the sim and restart it the problem does not recur. 

I have two screens with the sim running on one and Navigraph and other stuff running on the secondary.   Moving the mouse around the cockpit (not in VR) everything works as expected until the cursor is within 1" of any edge of the screen.

When the cursor touches the area within one inch of the edge - the screen image suddenly changes so that the center of focus is now where the cursor WAS at the point it touched the 1" boundary.  This happens most frequently when I am moving the mouse to the 2nd screen.  The mouse does smoothly transition to the 2nd screen but the primary screen center of focus remains at the point where the mouse left the primary screen.   

When I move the mouse back to the primary screen the center of focus travels with the mouse cursor.  The screen continues to scroll with the mouse cursor until I click anywhere on the primary screen inside the 1" edge boundary.

The same happens if I move the mouse into the 1" boundary area and then back into the primary screen - I have to click somewhere to stop the screen scrolling. 

As I said this only happens occasionally but if it does happen it is at the first screen I see in the sim and remains in effect until I restart the sim.

4 out of 5 flights I take do NOT have this problem and I cannot figure out what is causing it. 

I'll take a stab at this, I think there is a button setting with the mouse where you can click and move the view around with the mouse until you click that button again. This may be the setting you have and there are problems with your mouse. Something might be activating that click and hold setting that can happen when switching screens. How is that for a "stab" at a problem? 

2 hours ago, jimcarrel said:

I'll take a stab at this, I think there is a button setting with the mouse where you can click and move the view around with the mouse until you click that button again. This may be the setting you have and there are problems with your mouse. Something might be activating that click and hold setting that can happen when switching screens. How is that for a "stab" at a problem? 

I agree with your analysis - that is exactly how it is acting but I cannot find out how to prevent it.  Almost every time I start the sim it works correctly and the 'scroll when near the edge' does not happen.  But, something happens occasionally to enable the behavior and I then have to restart the sim to get normal mouse control back.  

Sounds like what occurs when the middle mouse button is clicked. At least for me. 

1 hour ago, Maladoror said:

Sounds like what occurs when the middle mouse button is clicked. At least for me. 

It is exactly like that - I use the middle mouse  button all the time.  But, once it happens due to getting too close to the edge - clicking the middle mouse button has no effect until I right click the mouse button.   The big problem is the image resets to look at the floor or right lower cockpit because my 2nd monitor is to the right and down from the main monitor.  Makes for difficult landings, particularly in IFR conditions.