I believe the security center has three or four parts you must uninstall to get rid of it. That's a lot of info, hypothetically, to be hypothetical about
Make sure there are no entries left in Add/Remove Programs.
Check McAfee's Web site to see if it has a "tool" to get rid of all the parts it installs. Norton has this same type of issue, even when you uninstall it, it's still there! Until you run the tool povide by, guess who- Symantec.