I understand that McAfee software turns itself off every time you re-start your computer, before we could proceed to fix this issue i need some basic information about your computer :
>What is the operating system installed on your computer ( Win Xp, Vista or 7)
>What type of internet connection you use (Wireless, cable or others)
>When McAfee shows that it has disabled itself, please open McAfee security center & find out why McAfee isn't protecting your computer. McAfee will give you a description about the problem. So please gather as much as information you can by opening McAfee security center & report the same in your next reply. Also attach a screen shot of McAfee security center if possible.