The default setting for the NIS 2010 "Tracking Cookies Scan" is "Ask Me". When I change it to "Remove", the setting sticks until I reboot. Then it reverts to "Ask Me". This appears to happen with 100% consistency.
I believe this behavior began with the v 17.5 update. (Actually, the "Tracking Cookies Scan" setting may have been introduced with the v 17.5 update. I know that at some point previously it was bundled with the "Low Risks" setting.)
Windows XP, SP3.