microsoft has their own security porgrams that run at the same time and we have not recieved any error messages. We are running XP Pro for 64-bit on a 64-bit system-AMD dual and we have 435G remaining on HD and 2G RAM. We went from free software and bought the pro for 2 yrs., so the script blocker was added in. I get a system message that our virtual memory is low, not like an error message, just a warning to close some aps which was never an issue until we bought Avast pro. Seems to me there is a huge memory leak? The lag issues occur if our system is not rebooted every day and still I am seeing some in my game that i didn't have before. Yes, lag issues go away after I disable avast pro.