I get 1 or 2 of the mail delivery failed message per day as well,but the funny thing is that before i installed Norton antivirus & was only protected by the windows xp firewall, i rarely used to receive any.Since installing the Norton antivirus my pc has slowed down so much,i wonder whether it was worth installing & it also quite often comes up with an internal program error & turns of the auto protect anyway.I have uninstalled & reinstalled several times as it tells you to & also downloaded the latest virus definitions etc & the so called fix for this problem. Regards, Andrew