I've been running v4.0.424.0 on XP Pro SP3 with no problems at all. I tried it out on Vista Business SP2 and it just won't behave. Kept coming up that the firewall & anti-virus weren't working needed re-installing. Wouldn't let me because not enough permissions. Wouldn't un-install either for the same reasons. This was on a clean install of Vista. Had to do another clean install with v3 and all is running as it should. Why can't ESET get it right?