FAQ in Windows OS
Windows security Unable to save permission changes on hosts Access is denied answer: close anti-virus software OpenGL 2.0 or greater required. Right-click the desktop, and choose "Screen resolution" from the popup menu. Click "Advanced settings" under Resolution. Click the "Properties" button on the Adapter tab: Click the "Update Driver..." button on the Driver tab: from:https://iscreensaver.com/help/notes/update_opengl_drivers/update_opengl_drivers.shtml#easyW7