New copy of OneCare

Jaap

I think it was discussed here before, but the messages are not on my
News server anymore.
Anyway a friend of mine had a copy of OneCare active over a year.
He bought a new copy (the new copy was cheaper than renewing the old
copy) but can not get the new copy to work.
He un-installed the old version but it still seems to be active in the
background.
What is the proper way to tackle this? Microsoft HD does not seem to
help him any further.
Thanks for your effort in advance.
Jaap