Running Windows XP on a one year old Vostro 220. Problem seems to have started after I replaced McAffee with Norton 360 per Comcast's changeover. I have since uninstalled Norton but the problem persists. Ran PSA which showed no hardware or memory problems. I believe Norton must have changed some of the registry values. I am running Norton on my laptop with Windows 7 but that is not a problem. No freezes. Help.