New W8 computer, Defender real time won't come on

I just setup a W8.1 system and when I tried to setup Defender I am told in the action center that defender real time protection is not running. When I select the big red button that says TURN ON, the system tries and comes back with "real time protection is turned off, you should turn it on". I checked TURN ON NOW, but it didn't come on. I want to use Defender as my anti-virus but I'm not sure it's on.

Are you by chance running another AV on the system? If so, this could cause a conflict. By default, if you are running another AV, Defender should be disabled.

http://www.eightforums.com/tutorials/21967-windows-defender-protection-turn-off-windows-8-a.html

There's a chance that something could be corrupt. Try running a SFC /SCANNOW. Be sure to run it 3X since it doesn't always fix everything 1st or 2nd time around.

http://www.eightforums.com/tutorials/3047-sfc-scannow-command-run-windows-8-a.html


This article has some helpful advice

Fix: Windows Defender is turned off or not working

Another possibility is that you have a virus that's preventing Defender from running. Perform a scan with the following tools:

Malwarebytes, The free version will work fine. Do a full system scan. When installing, be sure to uncheck the "Start my premium trial" box.

https://www.malwarebytes.org/free/

Also, TDSSKiller to rule out the possibility of rootkits.

TDSSKiller Download

Another good tool is AdwCleaner

AdwCleaner Download

This Defender problem is on a brand new computer that has not been used before so I don't think it is corrupted or has a virus. Maybe I should uninstall Defender and re-install from download, does that sound like a good idea?

I would try the fix listed above by Borg 386 first

Fix: Windows Defender is turned off or not working

Windows Defender is built into the system. It can not be uninstalled, only turned off or on.

http://www.eightforums.com/system-s...indows-defender-windows-8-1-a.html#post276232

Have you updated to all the latest MS patches?

The disk you used to install may have come with some pre-packaged software, including an AV. Double check to be sure you don't have another AV running in the background. Are you getting any error messages? If so, please post them. Also, check your event viewer to see if any error messages are being logged in relation to Defender.