^^Avira is a very good antivirus and is available from *www.freeav.com/ . There is a free version but it doesn't includes malware protection as far as i know. Use Avira along with Spybot Search and Destroy available at *www.safer-networking.org and/or ad aware from *www.lavasoft.com to get full protection under Windows XP. If you are running windows Vista Genuine copy, then update the definitions of Windows Defender first using windows update and do a through scan. If that doesn't works then download and use the software i previously mentioned.