They may have removed MS Security Essentials, what it is messing it up again.!
Find out for sure that you're actually using the newest version! You can find this out by opening CCleaner and looking at the upper-left. If it reads as v4.03.4151 then you're up-to-date and it shouldn't be possible for it to clean anything related to Microsoft Security Essentials anymore since both cleaners for it were completely removed starting with v4.03.4151.
And that is when the problem with MSSE started (again).
Find out for sure that you're actually using the newest version! You can find this out by opening CCleaner and looking at the upper-left. If it reads as v4.03.4151 then you're up-to-date and it shouldn't be possible for it to clean anything related to Microsoft Security Essentials anymore since both cleaners for it were completely removed starting with v4.03.4151.
I actually liked having the means to use ccleaner to remove some of those logs and scans. This sounds like one of those requests you read about over in the avast! threads. You need to know what your av is doing and have the means to clean it up. It didn't hurt anything having the mse option. All you have to do is update and scan and the warnings go away.
Another great example of the old he who sacrifices liberty for safety will have neither gag brought courtesy of the fear mongering and then because of this those of us who find it useful are at their mercy.
Previously there used to be a Microsoft Anti Malware box to uncheck under Utilities on the Applications tab. For me this has disappeared; so my MSE history gets deleted.
Having read this thread, I have tried to manually exclude the folders:
C:\Documents and Settings\All Users\Application Data\Microsoft\Microsoft Antimalware\Scans\History\Results\Quick
and
C:\Documents and Settings\All Users\Application Data\Microsoft\Microsoft Antimalware\Scans\History\Results\System
However, Browse button in the dialog window in CCleaner doesn't let me get beyond:
C:\Documents and Settings\All Users
It simply does not 'see' the Application Data folder and below. (I have looked around for a 'Show Hidden Files/Folders' type option without success.)
Subsequently found Application Data folder was 'hidden' so 'unhid' it and its subfolders in Windows Explorer, and this allowed me to add ~\Quick and ~\System to CCleaner's exclusions manually. Problem solved - I hope!
Thanks to Alan_B and Nergal for responses. (Operating system is Windows XP - I know I'm a dinosaur.)