I did a search on the Internet but could only find some old forum entries and posts. So I went to McAfee and under Tech support FAQ's which I hate and rarely find useful I found the page for "Your computer is at risk: Real-Time Scanning: Off " Document ID: TS100903. TS100903 from McAfee Site or as PDF from this site
I am running Windows XP with SP3 on an old Dell Desktop.
I had not installed any software nor restored the system in fact nothing but browsing so I was annoyed that McAfee decided to screw up.
Step 1 I had already tried that as that's how I found I had a problem!
Step 2 The Virtual Technician found two registry entries that needed fixing but that didn’t fix the Real Time Scanning issue.
Step 3 I tried to download the file oas-disabled-fix.cmd but I use Firefox and all I got was a page with this code
pushd "%CommonProgramFiles%\McAfee\VSCore"
mfehidin -i -x vscore.xml oas firecore scriptscan
popd
So I tried Internet Explorer which did download the file. But it still didn’t fix the problem.
Step 4 I read the long lists of incompatible software and couldn’t see anything that I was running that might conflict so moved on.
Step 5 Removal and re-install of McAfee.
Important!
Don’t start to remove McAfee until you are sure you can get to your account to download a new copy! Make sure you know your Username and Password before you remove the working version on your computer! (Part working is better than nothing working!)
I followed ALL the relevant Steps.
Removal of McAfee using Add/Remove Program
Downloaded and ran MCPR.exe(It opens a DOS window and on my machine took a while to complete but without any indication of operation so be patient.)
I didn’t get Cleanup Successful or Unsuccessful but did see a message to reboot so I guessed it was successful. Rebooted my machine.
Then I went to McAfee My Account and downloaded and installed the new download and Hey Presto the problem was fixed!
It took a couple of hours to go through all the steps but it DID solve the problem, Real Time Scanning now stays on.