Security Scan Plus is not needed and can be uninstalled via Control Panel > Programs > Uninstall a Program (Add or Remove Programs in XP). It is a sales tool that is an optional download with 3rd party software such as Adobe products amongst others.
Blank interfaces are usually cause by some sort of script failure involving Internet Explorer, which despit your default browser settings, is used by McAfee for display purposesd.
Check this article for help: TS101233
Siteadvisor is part of Total Protection and is meant to protect you against dangerous websites. If you wish to disable it, you can, simply go to your browser add-ons.