Okay today I finally upgraded to Windows 10. Everything looked fine and cool , then I suddenly decided to draw.
I open SAI - and ..... actually it didn't open at all. It did not worked !!!!
Then I've stubled upon this article here:
http://itsjustbeek.tumblr.com/post/125645677632/how-to-get-sai-working-on-windows-10
Now it works...