How To Stop Windows 8 Updates From Force Restarting Your PC
Step 1: Launch the Registry Editor by entering regedit in the Run dialog.
Step 2: Navigate to the following Registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
Step 3: Create a new DWORD (32-bit) with the following name NoAutoRebootWithLoggedOnUsers, and give it a hexadecimal value of 1.
Step 4: Reboot the system