Windows defender does not respond. Error 0x80070424

Hi ultramandude,

1. Since when are you facing this issue?
2. When exactly do you get the error code?

You cannot uninstall windows defender as it comes as an inbuilt program with Windows 7 by design.

Method 1:
You may try starting the windows defender in a clean boot state.To perform the clean boot follow the step 1 mentioned in the below article and then try checking in this clean boot state -

       http://support.microsoft.com/kb/929135

If the issue gets resolved check which non-Microsoft service is causing the problem; referring to the article and following other steps.
After you have finished troubleshooting, follow these steps to reset the computer to start as usual:

a. Click Start, type msconfig.exe in the Start Search box, and then press ENTER.
If you are prompted for an administrator password or for confirmation, type your password, or click Continue.

b. On the General tab, click the Normal Startup option, and then click OK.
c. When you are prompted to restart the computer, click Restart.

You may refer to the below links for assistance -
http://windows.microsoft.com/en-US/windows7/Turn-Windows-Defender-on-or-off
http://windows.microsoft.com/en-US/windows7/Turn-Windows-Defender-real-time-protection-on-or-off

Method 2:
You may also perform a SFC (System File Checker) scan. It will list any issues and helps resolve them –
Follow the below steps to perform a SFC Scan -

a.     Click  Start, click All Programs, click  Accessories, right-click Command Prompt, and then click  Run as administrator. If you are prompted for an administrator password or for a confirmation, type the password, or click Allow

b.     Type the following command, and then press ENTER:

sfc /scannow 

A message will appear stating that 'The system scan will begin'. Be patient because the scan may take some time

c.      If any files require a replace SFC will replace them. You may be asked to insert your Win7 DVD for this process to continue

d.     If everything is okay you should, after the scan, see the following message "Windows resource protection did not find any integrity violations" 

e.     After the scan has completed, close the command prompt window, restart the computer and check.

Check the below mentioned link for further guidance on SFC scan -
http://support.microsoft.com/kb/929833

Hope this helps.

Thanks,
Meghmala – Microsoft Support

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