I had this problem after installing the full version of McAfee Internet Security. If after running windows update try the following. Uninstall McAfee, make sure that Windows Defender is turned off and then reinstall McAfee. I think that there is a conflict between McAfee Site Advisor and Windows Defender as they both do similar functions.Providing that you don't turn Windows Defender on again you should not get this error message.
Although McAfee was preinstalled on my machine this problem only occurred when I paid for the full version. Out of interest before reloading McAfee I also tried Norton Internet Security - no problem. If you have paid for the full version of McAfee try my suggestion as you can re download McAfee from the net via your Mcafee account. If you have not paid or you can get a refund try Norton Internet Security.
Good luck
