PIFTS.EXE (Score 2, Interesting)

What I don't understand is that I got the PIFTS.EXE warning from McAfee, not Norton. I originally had an OEM Norton installation on my notebook PC, but immediately removed it, months ago, as our corporate standard is McAfee. But it seems that the removal was far from complete; on closer examination there's still a Norton process and service running, and apparently these triggered an update and the subsequent McAfee alert. So my question is, what is a Norton process doing on my computer, when I ran the default uninstall routine and it terminated normally?