This kind of behavior may occur if one of the following factors is true: 

1. Invalid file permission.
2. Invalid registry permission.

I suggest we perform the following steps to troubleshoot this issue:

Reset permissions 
========================
This step will reset the permission settings on this system, which may take us some time. Your patience is highly appreciated. 

Step 1: Download SubInACL (SubInACL.exe)

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1. Please download the subinacl.msi from the following link and save the installation patch on the Desktop: 

http://www.microsoft.com/downloads/d...inityDownloads

2. Please go to the Desktop and double click the downloaded file to install it. 

3. Please select the C:\Windows\System32 as the Destination Folder during the Installation. Later we will use this tool to reset the permission setting on the current Machine.

Step 2:

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1. Click Start, Run, type: notepad C:\reset.cmd and press Enter. Choose Yes when you are prompted. 

2. Copy the following commands and then paste them into the opened Notepad window:

@echo off

subinacl /subkeyreg HKEY_LOCAL_MACHINE /grant=administrators=f

subinacl /subkeyreg HKEY_CURRENT_USER /grant=administrators=f

subinacl /subkeyreg HKEY_CLASSES_ROOT /grant=administrators=f

subinacl /subdirectories %SystemDrive% /grant=administrators=f

subinacl /subkeyreg HKEY_LOCAL_MACHINE /grant=systems=f

subinacl /subkeyreg HKEY_CURRENT_USER /grant=system=f

subinacl /subkeyreg HKEY_CLASSES_ROOT /grant=system=f

subinacl /subdirectories %SystemDrive% /grant=system=f

@Echo =========================

@Echo Finished.  

@Echo =========================

@pause

3. After you paste the above commands, please close the Notepad window. Choose Yes when you are prompted to save the file. 

4. Click Start, Run, type: C:\reset.cmd and press Enter to run the commands we have pasted. 

5. You will see a DOS-like window processing. 

(NOTE: It may take several minutes, please be patient. When it is finished, you will be prompted with "Finished, press any key to continue")

After completing the above steps, please go to the Windows Update site to check whether the issue is resolved now.