This week I uninstalled NAV 2003 (due to expire shortly), no problem at all (on Windows XP Home)& installed AVG Free. I then had a major problem on Outlook Express - AVG mail scanner somehow stopped my server connection & I could not connect. Being impatient & annoyed I uninstalled AVG & reinstalled NAV 2003. All done without a problem & the bonus is that my NAV 2003 expiry date has jumped forward from April 2005 to April 2006 !! N.B I reinstalled NAV2003 from the original disc. Hope this helps.