May I know what is the message displayed in your security center : Is it "Am I protected YES" or "Your computer is secure " so that we could under the version of your mcafee software and guide you accordingly.
I have Your computer is secure (No action required) when I click on the security centre Icon.
You can't shut down SecurityCenter but you can shut down VirusScan and if necessary the Firewall also, although I do not recommend you do that. Usually only the Virus side of it is necessary in these case.
If your SecurityCenter looks like this:
Click Virus and Spyware Protection and then when that opens click Real Time Protection and the "Turn Off" button.
Tell it for how long you want it to stay that way and that's it.
If it's the older 2009 SecurityCenter double-click the taskbar icon to open SecurityCenter then click Advanced Menu (bottom)
Click Configure (left)
Click Computer & Files (op left)
Turn off VirusScan in the right=hand area and tell it for how long.
Don't forget to re-enable everything afterwards.