I'm using PerfectDisk10 with StealthPatrol feature on (it automatically defrags during system idle). I sometimes turn on Returnil (session lock on) for my child to "play" with the notebook. Then normally I'll restart my notebook before proceeding with my work. The question is how will turning on Returnil affect PerfectDisk, which automatically defrags, (or vice versa). Will this combination cause system instability?