Apple

Following the release of the Mac OS X security update to protect against the MacDefender fake antivirus, Intego’s security researchers discovered an interesting bug with the Security preference pane. A new preferences, Automatically update safe downloads list, was added in this security update. This setting tells Mac OS X to check every 24 hours, and on each restart, for new malware definitions in addition to the few that are already available. However, if you open the Security preference pane, unlock it, and wait for more than 30 seconds, any changes you make to this setting will not stick. Do the above, quit System Preferences, then open the Security preference pane and you will see that the setting will be as it had before your last change.

In addition, a log entry is written to the Mac’s Console logs:

System Preferences[1673]	*** xprotect: SMJobSetEnabled failed with: Error Domain=kSMErrorDomainLaunchd Code=2 UserInfo=0x200260100 "The operation couldn’t be completed. (kSMErrorDomainLaunchd error 2 - An operation failed in launchdadd for reasons that you probably can't do anything about. Maybe you should reboot.)"; {
    NSDescription = "An operation failed in launchdadd for reasons that you probably can't do anything about. Maybe you should reboot.";
}

You should be aware that this bug may override settings you make to this preference, and if for any reason you’ve left the Security preference pane opened for more than 30 seconds, you should check again to see if the change you made has stuck.