Hi,
I believe I have completely uninstalled McAfee from my Mac OS X Yosemite and yet when I try to install Norton Security I get the same message prior to uninstalling McAfee - 'We have detected incompatible security software installed on your computer. Please uninstall McAfee Internet Security and try again.'
I clicked on the McAfee uninstaller and it seems to have worked and this computer no longer appears on my McAfee account. I then moved the McAfee site adviser to trash.
Any help on this matter would be much appreciated.