I have one suggestion regarding the automatic updating occurring when you are in the middle of working on a project. If you click on the "Configure" button on the left side of the McAfee home screen, you will see an automatic update option shown on the next screen display. Click on the "Advanced" tab shown. On the next screen, you can change the way McAfee handles updates.
You can even disable the automatic function and do updates manually. Four options are shown. Yours may be set to update automatically whenever McAfee sends updates. I am a little puzzled the software is starting a scan automatically, however.
Hope this helps some.