How can I update my avast! Home 4.8 definition? Windows XP does not recognize avast! 4.8. I have some trojan files that are not detected by avast and need to be deleted.
The fact that the WSC doesn’t recognise avast shouldn’t stop it updating, avast should check for updates automatically when you first connect to the internet and every 4 hours if you remain connected.
Have (or did) you another AV installed in this system, if so what was it and how did you get rid of it ?
How do you know they are infected ?
You could also check the offending/suspect file at: VirusTotal - Multi engine on-line virus scanner and report the findings here the URL in the Address bar of the VT results page.