What is your operating system and service pack? How much installed memory (RAM) do you have and how much free hard drive space?
Go into SecurityCenter and turn of auto-updates
Double-click the taskbar icon to open SecurityCenter
Click Home, if there is any warning showing dismiss it
Click Updates >> Settings >> Turn Off
Go to Control Panel and uninstall all McAfee from the programs list.
Run the cleanup tool: http://download.mcafee.com/products/licensed/cust_support_patches/MCPR.exe and reboot.
Reinstall your McAfee software using the custom option if available for anything you may not need to be unchecked.
Try that. The current installation is obviously corrupted.