Hi, Coldmoon. After you cleared up the auto defragg crash i experienced, i am back using Returnil 2010 on my vista 64 bit System. I just started using Prevx 220.127.116.11. and everything was fine. All of a sudden my system froze and i received a warning that Prevx was trying to scan, not enough memory. It tried to give me another warning as it was shutting down. I could not see what it said. After rebooting my system windows security warning told me that Prevx was not showing any info. I rebooted again and everything was happy. I un-clicked Prevx auto scanning at a specific time and left scan on boot-up. I am also enabling Returnil manually as needed. I am not sure if anyone else has experienced this problem? I think both programs are keeper for me, if i survive the learning curve. I asked Prevx the same question also. Thank You In Advance, your Tech Support has been out standing.