Do you have Flow or Density set close to or equal to zero?
Have you calibrated your monitor since installing Windows 10? Or perhaps tried this: How do I change my monitor profile to check whether it’s corrupted?
Could you please check and see if the Flow of the Brush is 1, as it should be 100.
Also please make sure that the brush size is relevant.
Also many times when I go from the Library mode to the Develop mode, the programs shuts down.
That's often a symptom of an incompatibility between LR and your video card. If the other suggestions don't help, Go to System Preferences > Performance and uncheck Use Graphics Processor.