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Unfortunately, Windows Security Center isn’t very good, at least for the moment. There are many other, better anti-virus programs out there, some free, some you have to pay for. Many of them will do a much better job than Security Center in keeping your computer free of junk and viruses.
These programs can be quite demanding when they are running a scan. They require quite a lot of system resources to run, and attempt to access the same parts of the system, so Security Center doesn’t often play very nicely with a third party anti-virus program.
If you have one then it is wise to disable the built-in one and let the other program take care of business.
To only turn off the Windows anti-virus, go to the Windows Security Center via the Control Panel and click on Virus Protection. There should be an option there called “I have an antivirus program that I’ll monitor myself.” Select this and click okay.
That is all there is to it. Nice and easy for once.
If you want to go one step further and take care of all your security yourself then you could turn off Defender completely. While in the majority of cases Defender doesn't interefere with anti-virus protection, because it is an anti-spyware product, there is a case for turning it off if you use programs like SpyBot or AdAware. To be safe doing this you should have a third party firewall as well as anti-virus for full protection.
Navigate to services by right clicking the Task Bar and selecting Start Task Manager. Navigate to the Services pane, select Services in the bottom right, maximize the window and find Windows Defender in the list. Right click and select Disable then Ok. Stop the service and it won’t bother you again.

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