After critical Updates, Windows often needs to restart the computer to apply all changes, which however might not be in the interest of the user. To prevent Windows from auto-restarting (may it be to reduce annoyance or to prevent Windows from stopping unattended running applications), you can use a simple but effective registry entry. To apply it, open the Windows registry by entering regedit into a Run... prompt. On the left column navigate to the Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU key (you might have to create some of the keys if they have not been automatically created yet (right-click the key-tree for that)).
On the right panel, right-click to create a new DWORD-Value (32-bit) and call it NoAutoRebootWithLoggedOnUsers. Assign it the value 1 (which is the same in decimal and hexadecimal). key (you might have to create some of the keys if they have not been automatically created yet (right-click the key-tree for that)).
To reverse the effect, browse the same value again and change it to 0