Few days ago I changed to Windows XP Professional x64 Edition Evaluation copy Build 3790 (Service Pack 1,v.1433) and on this occasion I installed avest! version 4.6 Home Edition. Today a got the update (4.6.603) and after rebooting the PC, the Security Center of XP 64 changed automatically to green “Virus Protection → ON”.

               CONGRATULATION!!! :)