Moved this to your own new thread in the VirusScan section and retitled it for better attention.
When you removed F-Secure did you run their removal tool if they have one?
I'm assuming this is Windows 7 SP1 and that your version of Internet Explorer is IE9 rather than 8. (Even if you use another browser by default).
I mention that because McAfee SecurityCenter is actually an IE page so it relies on an up to date version thereof being installed and set to default settings.
What other security software of any type do you have installed and active? Any other popups or warnings I need to know about?
For a start try running the Virtual Technician to see if it finds and fixes any errors, sometimes it needs to be run twice or even 3 times.