The easiest way to change your firewall would be to go to avg.com and download there free trial.The avg firewall is automaticaly turned on and the microsoft firewall is turned off.If your running a home network and are sharing data through a hub youll need to adjust the firewall to accomodate this activity.There are videos that teach security basics at many sites on the web.Are you getting a virus warning or is the computer just crashing?