Windows Defender in Windows 8.1 Will Not Turn On

I tried both methods.  None of this worked.  I have also uninstalled "lenovo solutions center" just in case there was any AV function there.  Still, nothing works.  I can't even turn on defender in "services" and cannot turn it on to automatic (the option is disabled).  If you have any more suggestions, I will try them once more.  Thank you for your research.

Thanks.  Starting in safe mode has always meant my motherboard or disk was dying.  I am glad it has another function other than beginning the stages of grief.  :)  Will keep you posted.

Hi Bristlecone,

In most of the scenarios, this usually happens due to the conflicts with any third party security program installed on the computer. When you have a third party security program installed on the computer, it conflicts with Windows Defender and attempts to turn OFF/disable the Windows Defender services. This might lead to some other issues on the computer.

I understand that you had McAfee Security program installed on the computer and you have already removed it using the McAfee Removal Tool. I would like to know whether this removal process was successful and was it done from the Safe Mode.

Sometimes, even after using the uninstall utility in Normal Mode, it might not remove the third party security programs completely from the computer. However, when used this utility from Safe Mode, we have seen many instances where it removes the security program left over files and features completely from the computer.

So, as the first step, I would suggest you to boot the computer in Safe Mode with Networking. Please refer to the article given below and follow the steps given in it to boot the computer in Safe Mode with Networking:

***Windows Startup Settings (including safe mode)***

From Safe Mode with Networking, you may download the McAfee Consumer Product Removal (MCPR) tool from this link:

McAfee Consumer Product Removal (MCPR) tool

After downloading this tool, please run it and make sure that the removal process is successfully completed. After this, you may restart the computer in Normal Mode and then check if you are able to turn ON and open Windows Defender on the computer.

Hope this is helpful. If the issue still persists, please get back to us and we’ll be glad to assist you further.

In my research I found thru HP that you cannot have another program looking for Malware or other, so if I delete all other programs Windows defender works fine, but with any other program it will not.

When I try to turn Defender on in the action center, it takes me to the "system 32" folder and does nothing else.

I have read the entire forum and have not found anything that works.

The firewall is enabled and I have the latest system updates.

I am experiencing similar problems to Jennifer. I have uninstalled all the previously factory installed virus software using the Mcaffee removal tool, I have gone into services and gotten the 577 error, I have tried running Windows Defender from the command prompt in hopes that it would shake something loose, but still no Joy.  What in the world is preventing Windows Defender from starting back up?  Should I reinstall windows 8.1?   It really shouldn't be this difficult, but it is.