How to Disable Automatic Reboot for Automatic Updates

Source: http://answers.microsoft.com/en-us/windows/forum/windows_7-windows_update/how-to-turn-off-reboot-after-automatic-update/43b2abf8-6820-49df-a149-657190fdeb93
Snapshot: December 9, 2012, 04:00 PM

Intro: This post shows you how to turn off the default behaviour of restarting after an automatic update in Windows 7 to avoid finding your work of several hours trashed by an automatic update restart.
Run gpedit.msc (Computer Configuration > Administrative Templates > Windows Components > Windows Update) and enable the setting that reads "No auto-restart with logged on users for scheduled automatic updates installations".

If you decide to select the Download updates but let me choose... option in Automatic Updates settings instead, no updates will install without your explicit Approval.

If settings for AutoUpdate or Group Policy (gpedit.msc) didn't help or weren't available (like for Win 7 Home Premium), the next step is to edit your registry. Sounds scary and time consuming? Don't worry, it's safe and takes 1-2 minutes. Just follow directions closely.

1. Be safe, create a restore point [Control Panel > System and Security > System > System Protection > Click Create].  Or use whatever your preference is (create system image, use a backup program, etc.)

2. Also backup your current registry.  [Start > Search for regedit and open.   In the Registry Editor window hit File > Export.  Make sure "All" bubble on bottom left is checked.  Type regbackup for name and click Save].

After the backups are done:

3. Start > Search regedit and open.  In the Registry Editor window, go to HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\WindowsUpdate.  If you don't have WindowsUpdate in the left pane (as mine didn't), just right click on Windows, click New, Key, type WindowsUpdate and hit Enter.

4. In the left pane, right click on WindowsUpdate, click New, Key, type AU and press Enter.  (Skip this step if you already have AU in the left pane).

5. In left pane, click AU.  Right click in an empty space in the right pane and click New, DWORD (32-bit) Value.

6. Type NoAutoRebootWithLoggedOnUsers and press Enter.

7. Right click on NoAutoRebootWithLoggedOnUsers and click Modify.

8. Type 1 and click OK.