can't install SP3- "access denied"

Hi,

I tried to install XP Service pack 3, from the automatic Windows update, and am getting "access denied." I disabled firewall and AV program beforehand, and in User Accounts I disabled fast switching between accounts. I just recently did the full malware removal protocol here and came up clean.

What could possibly be causing this error? The Windows Update logfile for this event is rather huge, so I didn't know if I should post it here.

Thanks in advance,
Karen

 

http://support.microsoft.com/kb/949377

http://support.microsoft.com/oas/default.aspx?ln=en-us&prid=11273&gprid=522131