Funny thing.
I'm using Windows 10 on two PCs too, and none of them shows this issue.
Just for reference, there's a "mouseUse" setting in conf.ini which per default equals "2", which means that IL-2 uses an "internal" mouse cursor (the yellow one).
"1" would be the windows default cursor (the white one) but using it rarely makes sense.
Now the thing about the yellow il2 mouse cursor is this:
When IL-2 gets started in "mouseUse=2" mode (default, yellow cursor), it installs a low level hook on the system mouse.
Since IL-2 doesn't use multithreading to handle events like mouse cursor movements, during launch time of IL-2 the mouse gets stuck until the game loads up to a certain percentage.
At 70% for the first time mouse movements will become possible.
That's also the stage where IL2 will recognize for the first time that it might have lost input focus (Ctrl-Alt-Del or Alt+Tab).
As a result, once you kick up IL2 the mouse freezes system wide until IL2 reaches 70%.
If you Alt+Tab or Ctrl+Alt+Del or "Windows key" out of the game before it reached 70%, you will see the Windows Mouse cursor (the white one) but it cannot move since IL2 isn't able to recognize that it lost focus and therefore cannot release the mouse hook at that stage.
At this point however all you have to do is to wait for IL2 to load up to 70% (this can even happen in the background where you don't see it) and the mouse cursor will start moving again.
Best regards - Mike