For more information, i am running Windows XP operating system as well as my product is McAfee Plus 2012.
Open SecurityCenter by double-clicking the taskbar or desktop icon then click 'About' and post what it says for version and DAT under VirusScan please.
Try running the Virtual Technician as sometimes it can fix things. Run it again if it says it can't fix something.
Also check your System Clock is accurate both time and timezone-wise.
I trust this is XP SP3?