To Daphnej & others :
For those with XP SP2 & its "Security Center", it is best to
select the "Monitor the Antivirus Program myself" setting
based on the pcworld.com article at :
www.pcworld.com/ news/article/0,aid,119376,tk,021105a,00.asp .
I think I saw a news item somewhere that Microsoft
"fixed" the "problem" mentioned in the article, but
who knows !?