I will tell you some reasons
1.Your computer runs slow.
2. You are not instaling latest .Net framework.
3. Your PC has installed an older version of bluestacks.
4. If you don’t have administrator privileges, BlueStacks error may appear that makes your PC shut down automatically.
Method 1: if your PC runs slow and you’re running several applications in the background, it may fix blueStacks stuck on initializing error. Make sure that closed any unnecessary applications and run only Bluestacks.
Method 2: Download and install the latest version of Bluestacks
Method 3: Restart bluestacks
You can learn more step by step fix your problem while using bluestacks at this guide http://howtoinstallwindows10.com/bluestacks-stuck-on-initializing-windows-10/
Hope you fix this error